Moscow , Russia -LRB- CNN -RRB- -- Investigators have found `` elements of an explosive device '' at the site of the derailment of an express train in Russia and believe an act of terror caused the deadly incident . The derailment killed at least 26 people and injured about 100 , but there was no immediate word on who or what group might have been behind the action . `` One can say with certainty that that was indeed an act of terror , '' Vladimir Markin , spokesman for the investigative committee of the Russian prosecutor 's office , told CNN . He would not elaborate on exactly what kind of `` elements of an explosive device '' the investigators discovered earlier , but said the crater found beneath the railroad bed was `` 1.5 meter by 1 meter in size . '' Later Saturday morning , a second device went off on nearby tracks going the opposite direction , Vladimir Yakunin , head of Russian Railways , told Russian TV . He said no one was injured in the smaller explosion . Markin said investigators are `` studying the site of the accident , questioning the witnesses and conducting all kinds of forensic and technical examinations . '' Federal Security Service Director Alexander Bortnikov said , `` Criminology experts have come to a preliminary conclusion that there was an explosion of an improvised explosive device equivalent to seven kilos of TNT . `` Several leads are being pursued now . A criminal case has been opened under Article 205 -LRB- `` terrorism '' -RRB- and Article 22 -LRB- `` illegal possession or storage of weapons or explosives '' -RRB- of the Russian Criminal Code . '' Russian Interior Minister Rashid Nurgaliyev said on TV that there are possible suspects in this crime . `` There are several people who could be involved in this crime , '' he said . One of them , he said , is a `` stocky-built man of about 40 years old , with red hair . '' `` There are some traces left at the crime scene which could help in the investigation , '' he said . `` We are getting a lot of information now , and I am very thankful for people who have responded to our requests to render their assistance in investigating this crime . '' A total of 681 people -- 20 of them employees -- were on the Nevsky Express as it traveled from Moscow to St. Petersburg on Friday night . The Nevsky Express is Russia 's fastest train , equivalent to a bullet train . The crash happened at 9:25 p.m. -LRB- 1825 GMT -RRB- when the train was 280 kilometers -LRB- 174 miles -RRB- from St. Petersburg , Russian state radio said . At least three carriages carrying more than 130 people derailed and turned on their sides , and emergency workers were working to free anyone who may still be trapped inside . Yakunin told Russian TV that the company will pay a compensation of 500,000 rubles -LRB- $ 17,240 -RRB- to the victims ' families and 200,000 rubles -LRB- $ 6,897 -RRB- to those injured . The crash happened 44 minutes after another high-speed train , the Sapsan , had successfully traveled from Moscow to St. Petersburg on the same rails , a representative of the Russian Transport Police said during a video conference call Saturday . In August 2007 , an explosion on the tracks derailed the Nevsky Express , injuring 60 people in what authorities called a terrorist act . About 27,000 passengers on 60 trains were facing delays Saturday as a result of the accident , Russian State TV reported . CNN 's Maxim Tkachenko contributed to this report