At least three people were killed and ten others wounded in a suspected grenade attack on a religious gathering in northern Indian state of Punjab today.

The 10 injured were taken to the hospital and the bodies of the three victims sent for post-mortem, our New Delhi correspondent reports quoting Surinder Pal Singh Parmar, a senior police officer of Amritsar.

Quoting witnesses, Indian media said two unidentified men riding a motorcycle, with their faces covered, hurled a grenade at the Nirankari Bhawan in a village near Amritsar city in the morning, where a religious ceremony was going on at the time, and fled.

The venue of the gathering was just eight kilometres from the Rajasansi airport in Amritsar. About 500 people were reportedly in the gathering when the attack took place.

The Nirankari religious sect is an offshoot the Sikh community distinct from Akalis. The head of Nirankari group was killed in a terror attack in north Delhi's Nirankari Colony way back in early 1980s.

The incident took place in the backdrop of a high alert issued by the police in Punjab that six to seven terrorists entered the state.

While the police are yet to term as a terror strike, they are watching the CCTV footage looking for clues to identify the attackers.

"The incident is an attempt to disturb peace in Punjab. All the security agencies are on high alert and coordinating with each other to maintain peace," said Sunil Jakhar, the President of Punjab unit of the state's ruling Congress party.