Five persons were injured, one seriously, in a crude bomb attack at a chemist shop in Nagaland's commercial hub Dimapur on Monday, police said.

"Five persons were injured, including one critically. They have been admitted in hospital," Commissioner of Police Alimasunep Jamir told IANS.

"Investigation is on to ascertain the identity of those behind the attack," Jamir said.

Intelligence officials said the bomb attack could be a fallout of non-payment of extortion money.

No group has claimed responsibility for the attack.