New video footage has emerged of tourists fleeing in fear after they hear the sounds of gunshots following a terror attack on a Tunisian museum. The terrifying short film shows how the visitors are enjoying a guided tour of the National Bardo Museum in Tunis before gunshots are fired, making the group jolt with surprise. Initially not sure what is happening, they hesitate and the tour stands still - but as the horror dawns on them, the group begin to run for their lives. Terror: Two tourists hold tightly onto each other as they run away from the sounds of gunshots during the attack on the National Bardo Museum in Tunis, Tunisia . Disturb: The Italian group were being given a guided tour on the museum when they were disrupted by the sound of gunshots . Attack: The camera points towards the sound of the gunshots, where terrorists had opened fire on unsuspecting visitors. Isis have claimed responsibility for attack which killed 21 people . Italian publication La Repubblica posted the footage, which was shot on a device owned by tourists Marcello and Maria Rita Salvatori. The camera continues to roll as the tourists sprint away from the sound of gun shots, before congregating in hushed quiet in a small room as they try to work out what has happened. The new footage has emerged on the same day as Tunisian government and museum officials announced they have had to delay the re-opening of the centre because of security concerns. Afraid: The tourists huddle together after rushing away from the sound of guns being fired, and stay quiet to try and work out what is happening above . Head of communications at the museum Hanene Srarfihas revealed she expected the museum to open on Sunday instead. She said: 'We have been surprised at the last minute, but the interior ministry says that for security reasons we cannot receive a large number of visitors.' However an official ceremony marking the reopening of the museum went ahead on Tuesday as planned and was attended by Tunis residents, urging tourists to return to their country. Protest: Tunisians gather outside the National Bardo Musuem to demonstrate and plead for tourists to visit the country again . Demonstration: The campaigners carried signs and placards outside the centre, which was attacked by terrorists last week. Isis have claimed responsibility . Unsafe: While a ceremonial re-opening of the National Bardo Museum took place on Tuesday, security fears mean authorities had to cancel its formal re-opening to the public . Tension: A woman wrapped in the flag of Tunisia chants slogans during the demonstrations outside the National Bardo Museum, while security forces carrying guns control the entrance to the centre in Tunis . They shouted slogans and held placards, some of which read: 'Visit Tunisia' and 'Muslims are not terrorists'. Another said: 'I'm Tunisian. Islam is my religion and I love you ALL. Visit Tunisia. Peace.' Innocent: Tunisian children chant during the reopening of the Bardo Museum following deadly attacks in Tunis . Dress: Tunisians dressed in traditional costumes gather outside the National Bardo Museum during ceremonial reopening . The terror attack killed 21 people - including 17 cruise ship tourists - and two gunmen were killed by police. On Sunday Tunisia's president President Beji Caid Essebsi said a third attacker - the suspected mastermind - is still on the run following the massacre. Tight security: Tunisia's national museum (pictured with heavily armed Tunisian policemen on guard outside) has delayed a planned reopening after last week's attack on foreign tourists due to security concerns . Footage: News of the delayed reopening comes after a CCTV video was released showing a pair of gunmen roaming the Bardo, and appearing to allow one visitor to go free . Bardo curator Moncef Ben Moussa said that the museum is delaying the reopening, and it will probably reopen on Sunday instead. He did not elaborate on what prompted the last-minute change, citing only logistics and security. Authorities have arrested several people in the attack, the worst in Tunisia in 13 years, and are still hunting for the suspected mastermind. Officials have said none of the museum's major archaeological treasures suffered damage. Over the weekend President said the attack involved 'three aggressors' and the third man escaped. He was speaking live with French network iTele from inside the museum. Suspects have been arrested over the attack but it was previously believed just two gunmen launched the attack on the museum. The news comes after a video was released of the pair roaming the Bardo. The one-minute video posted on the government's Interior Ministry Facebook page shows the two men scurrying through the Tunis museum, carrying assault rifles and bags. Statement: On Sunday Tunisia's president President Beji Caid Essebsi (pictured) said a third attacker - the suspected mastermind - is still on the run following the massacre . Shattered: The walls and windows were peppered with bullet holes while unused grenades lay scattered among debris following last week's attack on the Bardo Museum in Tunis . One of the attackers is wearing a baseball cap and a heavy jacket, while the other wears a red hooded jumper and tracksuit pants. At one point, they encounter another man with a backpack walking down a flight of stairs. They briefly acknowledge each other and let the unidentified man walk free before unleashing the deadly attack in the country's largest museum. The video also shows stills of the dead gunmen - named as Yassine Laabidi and Hatem Khachnaou - who were killed in a firefight with security forces, including a picture indicating at least one was wearing an explosive belt. Police responding to the attack shot and killed the two gunmen. They were identified as Tunisians in their 20s who had trained in Libya. Essebsi said the extremists who have recruited about 3,000 Tunisians to fight in Iraq and Syria have no credible connection to Islamic belief. He said his country was at war with them. 'When war is brought upon us, we will wage war,' he said. Yassine al-Abidi had breakfast with his family as normal on morning he and his fellow terrorist Hatem Khachnaoui attacked the Bardo museum last Wednesday killing 21 people and injuring more than 60 others . Graphic: Al-Abidi and Hatem Khachnaoui pictured were both killed after a four-hour standoff with special forces . ISIS claimed Wednesday's attack on foreign tourists in Tunis, the deadliest involving foreigners in Tunisia since a 2002 suicide bombing on the island of Djerba. Tunisian fighters make up a disproportionately high number of foreign recruits to ISIS in Syria, with as many as 10,000 having signed up. The government said the two gunmen had trained in jihadi camps in Libya before the attack inside the heavily secured Tunisian parliament compound. Police in Tunisia have arrested five people described as directly tied to the two gunmen. Four others said to be supporters of the cell were also arrested in central Tunisia, not far from where a group claiming allegiance to al Qaida's North African branch has been active. ISIS issued a statement and audio on jihadi websites applauding the dead gunmen as 'knights' for their 'blessed invasion of one of the dens of infidels and vice in Muslim Tunisia'. As investigations into the massacre continue, Tunisian security officials have been asked why the world-famous museum was completely unprotected. The government now plans to deploy the army to major cities to bolster security following the shootings.
New video shows moment tourist group hear the gunmen opening fire . Visitors were listening to guide when startled by sound of shots being fired . After initial confusion, the tourists realise the danger and run for their lives . 21 people killed at the National Bardo Museum during attack on March 18 . Museum's re-opening has been delayed during to security concerns . Tunisians demonstrated outside centre urging tourists to support country . Two gunmen were killed by police by Tunisia's president said a third suspect - the suspected mastermind - is still on the run .