Reading's dream run in the FA Cup has been soured after video emerged of a supporter hurling a flare towards Bradford City supporters at the Madejski Stadium. The Royals were clinical in beating Bradford 3-0 in Monday night's quarter-final replay to reach their first FA Cup semi-final in 88 years - they face Arsenal on April 18 or 19 - but their joy has been tempered by several unsavoury off-field incidents. During the game a Bradford fan was arrested after allegedly racially abusing Reading's Garath McCleary, while one home fan invaded the pitch and goaded Bradford supporters. There was also a mass pitch invasion by home fans after the final whistle and the new video clearly shows that a flare was hurled into the South Stand where the travelling support were. VIDEO Scroll down to watch the incident . Blue smoke can be seen billowing from a flare carried onto the Madejski Stadium pitch on Monday night . The flare leaves a trail of smoke as it is hurled into the crowd during the pitch invasion . The trail of smoke shows the flare's path into the South Stand, where Bradford's support was sat . The flare was spouting smoke which matches Reading's signature royal blue kit colour. Thames Valley Police confirmed on Tuesday that an 18-year-old man from Bradford had been arrested and cautioned for carrying a flare - but this occurred outside the ground before the match. No further arrests have been made concerning the incident after the game. A  spokesman said: 'An 18-year-old man was arrested on suspicion of possessing a firework while trying to enter a designated sports ground. 'He was given a caution.' The video attracted angry and dismayed comments from fans as it was widely shared on Twitter. One user, Chris Hilton, who describes himself as a Bradford season ticket-holder, said: 'A flare getting chucked into the #bcafc end from the Reading fans #StayClassy' A man is pictured holding a flare while on the pitch at the Madejski Stadium after the full-time whistle . The man's arm is soon pictured raised and the gaze of other nearby fans suggest he has thrown the flare . It is unclear whether this is the fan who threw the flare into the Bradford supporters' end at the Madejski . The pitch invasion was just one of several unsavoury incidents which marred the match . A man raises a flare above his head while on the pitch after the FA Cup quarter-final replay . An eyewitness told MailOnline: 'Celebrating your team’s victory is one thing, goading the opposition fans with sick taunts is another. 'There were kids showing off lighters and mouthing the words "fire, fire, fire" which we all knew was a reference to what happened at Bradford in 1985. 'One youth quite clearly launched the flare into the crowd, while, as they had done all game,  the stewards sat back and allowed it to happen.' Gary Lineker, who hosted the BBC's live coverage of the match from a studio at the Madejski Stadium, had described the pitch invasion as 'lovely scenes' in the immediate aftermath of the match. Lineker's comment was surprising considering the obvious safety concerns raised by a pitch invasion. The invasion sparked angry exchanges between both sets of supporters as stewards prevented furious Bradford fans from entering the pitch to confront jubilant Reading supporters. Twitter users expressed their dismay at the video, which was widely shared on social media . Reading comfortably strolled into the FA Cup semi-finals with a 3-0 win. Click here to read the full match report . Supporters proceeded to throw missiles, including bottle of waters, on to the pitch. Earlier, a pitch invader goaded travelling supporters which caused Bradford fans to throw more missiles onto the pitch. Police confirmed that a 20-year-old man from Wokingham is still in custody after being arrested on suspicion of 'going on to playing area at a football match' at around 9pm. Two other arrests were made on the night, one 24-year-old from Bradford on suspicion of possession of a Class A drug and a 27-year-old man from Bradford on suspicion of being drunk and disorderly in a public place before the match. Reading keeper Adam Federici was seen handing a coin to a steward guarding Bradford fans. The pitch invasion also follows the ugly scenes at Villa Park earlier this month, when there was chaos as thousands of Aston Villa supporters piled on to the pitch following victory over rivals West Bromwich Albion in their FA Cup quarter-final. Fabian Delph claimed he was bitten, while Boaz Myhill, Craig Dawson, James Morrison and Callum McManaman all appeared to be barged aggressively. And video footage appeared to show further player altercations with on-rushing fans. Concerning the alleged racial abuse of McCleary, a spokesman said: 'A 36-year-old man from Bradford was arrested. We had reports of indecent or racist chanting.' The man was freed on bail until next month. Reading's celebrations were marred by an allegation of racist abuse towards winger Garath McCleary . Fans invaded the pitch after full-time as Reading secured their place in the FA Cup semi-finals . Hundreds of supporters ran onto the pitch after watching Reading secure an FA Cup semi-final spot . Bradford players applaud their supporters after full-time in the FA Cup quarter-final replay . Referee Mike Jones collects a plastic water bottle which was thrown onto the pitch by Bradford fans . The incident occurred five minutes before half-time when McCleary tried to retrieve the ball from the Bradford end. McCleary, a Jamaica international who scored the second goal after his shot took a big deflection, was shocked by something a fan said to him. The winger immediately informed the referee's assistant, who subsequently told fourth official Andre Marriner. Marriner relayed the information to a senior Reading security chief, who is understood to have promptly ensured the fan in question was ejected from the stadium. The supporter was then arrested. In confirming the incident, a Reading statement read: 'An incident was reported to the match officials just before half-time, who in turn told Reading staff. A man was then arrested and ejected during the half-time interval. The FA will wait for referee Mike Jones' report before deciding on what course of action to take, if any, this morning.' Reading players mob goalscorer McCleary during the home side's 3-0 victory . Hal Robson-Kanu (centre) prepares to wheel away in celebration after scoring the opener past Ben Williams . The man arrested faces a lifetime ban from City games if found guilty, according to chairman Mark Lawn. 'I heard about that and when we find out who it was we will take action,' said Lawn. 'I understand the police are prosecuting so we can't do anything at this stage, but if that person is found guilty we will take action. 'There is no place for that in the game, it is unacceptable. 'I would think we're looking at a lifetime ban if he's found guilty but that decision can only be made after consultation with the club's board.'
Video emerges showing flare being hurled into Madejski Stadium stands . Flare was thrown by a man on the pitch following the final whistle . Reading's FA Cup win over Bradford was marred by several incidents . Mass pitch invasion was described as 'lovely' by Gary Lineker on BBC . An arrest was made after alleged racial abuse towards Garath McCleary .