A bomb exploded at a busy bus station in south Nepal, killing two people and wounding 12, officials said Sunday.

The bomb exploded as passengers waited for a bus at the station Saturday night at Chandranigahapur town, about 150 miles south of the capital, Katmandu.

Rautahat district's chief official Durga Bhandari said two of the injured were in critical condition and 10 others were in serious condition and getting treatment at local hospital.

"We have stepped up security in the area and have mobilized dozens of policemen to hunt for the assailants," he said.

A little-known armed outfit calling themselves Tarai Army called the local newspaper to claim responsibility.

Bhandari, however, said he had no information about who was responsible. "We are investigating," he said.