Patna, Jan 23 (IANS) Two people -- a woman and a police constable -- were killed and more than a dozen injured in a bomb blast in a Bihar court Friday. It was not a terror attack but was aimed at helping two undertrial prisoners escape, police said.

Earlier, it was said that three people were killed but police later clarified that one of four seriously injured was mistakenly identified as dead initially due to panic.

A district police officer said a crude bomb exploded within the premises of the Ara civil court in Bhojpur district, about 60 km from the Bihar capital.

The injured were rushed to the local civil hospital for treatment. Some of them were later referred to the Patna Medical College and Hospital when their condition deteriorated.

Security in courts across the state was beefed up following the blast.

Additional Director General of Police Gupteshwar Pandey told the media that the bomb was carried by a woman, one of the victims.

"Police have found a mobile phone near the mutilated body of the woman," he said.

Pandey said it was neither an attack by terrorists nor by Maoists.

"This incident was a criminal act to help two undertrial prisoners escape when they were being brought to the court from the district jail," he said.

Pandey, however, denied that the woman was a suicide bomber. "It was a coincidence that the bomb exploded in her bag when she was trying to adjust it," he said.

According to an official from the Chief Minister's Office, the union home ministry has sought a report from the state government.

Chief Minister Jitan Ram Manjhi expressed serious concern over the blast and asked the state chief secretary, police chief and home secretary to tighten security to prevent such incidents in future.