Home Minister Rajnath Singh Monday reviewed security situation in the country, particularly in Punjab where three people were killed and 20 others injured in a grenade blast, officials said.

Senior officials of the Home Ministry and security agencies briefed the home minister on the explosion at a religious gathering near Amritsar on Sunday, an incident which police are treating as a "terrorist act". The home minister directed the officials to provide all assistance to the Punjab government in their investigation to nab the perpetrators of the crime, a home ministry official said.

Singh was told that a team of the National Investigation Agency has already visited the blast site along with their investigators and explosive experts. Three persons, including a preacher, were killed and 20 others injured when two-motorcycle borne men threw grenade on a religious congregation on the outskirts of Amritsar.

The incident took place inside the Nirankari Bhavan's prayer hall at Adliwal village near Amritsar's Rajasansi, police said. A religious congregation of the Nirankari followers was being conducted inside the Bhavan at the time of the incident.  The Sant Nirankari Mission is a spiritual organisation and the Bhavan lies close to the Amritsar international airport and the Indo-Pak border.