Hunt is on for perpetrators of Russian blast

>> mike viqueira in washington.

>>> in russia tonight rescuers and police are working side by side after a powerful bomb blew a high-speed train off the track. the attack killed 26 people. it took place late last night about 150 miles from st. petersbu petersburg. nbc's stephanie gosk has our report.

>> reporter: in the bitter russian cold today, rescue workers were still pulling bodies from the wreckage. the nev ski express, a popular train for businessmen and government officials was attacked on its way from moscow to st. petersburg. the train was hit at 9:30 at night 200 miles north of moscow. moments later the conductor phoned russian television. there was an explosion, he says. i don't know what we ran over. everything is in smoke. the cabin blew up. at least 26 people were killed, nearly 100 injured.

>> translator: i saw 20 seriously injured people, some being carried away by hand.

>> reporter: with more than a dozen still missing, the death toll is expected to rise. a criminal investigation is under way.

>> translator: we have to act fast in order to secure as much evidence as possible.

>> reporter: no one has claimed responsibility, but both muslim rebels and nationalist militants have targeted mush sha before. in 2007 , the same train tracks were bombed by an islamic group . 30 people were injured. five years ago chechen rebels attacked an elementary school . among the dead, 186 children.

>> terrorist activity continues constantly. aimed mostly at sensitive targets.

>> reporter: like the neve ski express leaving many russians wondering when and where they will be hit next. stephanie gosk, nbc news, london.

>>> three americans were killeded to