The Punjab Police on Sunday said the grenade attack at a religious congregation in Amritsar that killed at least three people and wounded 20 appears to be an act of terrorism. The blast occurred during a gathering at the Nirankari Bhawan in Adliwala village, the Hindustan Times reported.

The Nirankaris are followers of an independent spiritual movement who claim to be unaffiliated with any religion and reject the authority of Sikhs over them, according to The Indian Express.

“This incident appears to have a terror angle,” Director General of Police Suresh Arora told PTI. “Because it is against a group, not an individual. There is no reason to throw a hand grenade on a group of people, so we will take it as a terrorist act, till proven otherwise.” There was no “specific input” about the attack, he added.

Two people on a bike lobbed a grenade at the congregation, Inspector General of Police (Border Range) SPS Parmar told The Times of India.

Earlier in the afternoon, Chief Minister Amarinder Singh asked the state home secretary and senior police officials, including Arora, to visit the spot for investigations. “My heart goes out to victims of the Amritsar bomb blast and their families,” Singh said. “My government will give Rs 5 lakh to kin of each of the dead and free treatment to the injured. Have asked district administration to extend all help.”

Union Home Minister Rajnath Singh said the attack has “deeply anguished” him. “It is a reprehensible act of violence,” he tweeted. “Strongest possible action will be taken against the perpetrators of this crime.”

State Congress chief Sunil Jakhar also offered his condolences. He called the attack “an attempt to disturb peace in Punjab”. “I believe all the security agencies should stay alert and coordinate with each other to maintain peace,” Jakhar added.

Punjab has been on alert following an input that a group of six to seven militants of the Jaish-e-Mohammad are in the state. Zakir Moosa, the commander of a militant group affiliated with the al-Qaeda, is also reportedly hiding in the state.

Last week, four people hijacked a car at gunpoint near Madhopur in Pathankot district. Police in Pathankot, Gurdaspur and Batala were put on high alert following the incident.