An alert has been sounded in Punjab after a rocket-propelled grenade was fired at the third floor of the headquarters of the Punjab police intelligence wing in Mohali on Monday.

No one was injured in the 7.45pm attack on the heavily guarded building in Mohali’s Sector 77. On Tuesday, the police said arrests had been made and leads found.

Opposition parties called on chief minister Bhagwant Mann to get his priorities right and focus on the state.

“Inexperience and misplaced priorities of the Aam Aadmi Party government are being exploited by terrorists who seem to be raising their heads in Punjab,” Congress state unit chief Amarinder Singh Warring said in a statement.

Mann said the strictest punishment would be meted out to those trying to spoil the state’s atmosphere.

Director-general of police V.K. Bhawra said they had got a few leads and the case would be solved soon. At a meeting, the DGP informed the chief minister that some suspects had been taken into custody for interrogation.

Mann said nobody would be allowed to disturb the peaceful atmosphere of Punjab, adding that a few inimical forces were constantly trying to foment trouble across the state but they would never succeed.

After his meeting with the DGP, the chief minister said: “Some arrests have been made and more will follow. Whoever tries to spoil the atmosphere of Punjab will not be spared and the strictest punishment will be given to them, which their coming generations will remember.”

Later, after a meeting with senior officials at the intelligence wing headquarters, Bhawra told reporters in Mohali that a projectile had hit the building and the explosive used in it appeared to be TNT (trinitrotoluene).

“There was nobody in the room when the incident occurred. The impact was on the wall,” the DGP said. “But it is a challenge and we are making all-out efforts to solve the case.”

To a question on whether it was a terror attack or whether there was a Khalistani angle, Bhawra said whatever comes out of the investigation, “we will let you know”.

“We have leads and we will soon solve this case,” he said.

A preliminary investigation has pointed to the involvement of two men who came in a car and used a rocket-propelled grenade to fire at the building.

The incident is being seen as a major intelligence failure as the building houses the state counter-intelligence wing, special task force, the anti-gangster task force and some other units.