At least 12 people, including two SSB personnel, were injured in a grenade blast, reportedly carried out by ULFA(I) militants, in front of a shopping mall in the heart of the city on Wednesday evening, officials said.

"As per our information, 12 persons were injured in the explosion. Out of them, five are (undergoing treatment) at Gauhati Medical College and Hospital. The condition of one of them is serious. Five others with minor injuries were admitted to a private hospital. The state will bear expenses of their treatment," Minister of State for Health Pijush Hazarika said.

Hazarika visited the hospital and enquired about the treatment of the injured.

Two others suffered eye injuries and they were taken to an eye hospital, Kamrup Metropolitan Disaster Management Authority CEO Bidyut Bikash Bhagawati said.

Several of the victims were yet to be identified.

The site of the explosion is at the heart of the city and next to the Shraddhanjali Kanan park, where a large number of people usually gather in the evening.

"The injured include two SSB jawans. There is also one college-going woman among the injured," Bhagawati said.

The Sashastra Seema Bal (SSB) jawans were on patrolling duty with Assam Police personnel in the area.

"It is suspected that the grenade was hurled at the police party," Director General of Police Kuladhar Saikia told reporters at the spot.

He said Chief Minister Sarbananda Sonowal has ordered him to carry out a speedy investigation and arrest the perpetrators of the crime.

Local TV channels reported that ULFA(I) chief Paresh Baruah claimed responsibility for the blast, but the police refused to confirm it, saying a detailed investigation will ascertain the claim.

Saikia said militant groups such as ULFA(I) and NDFB (S) have suffered a jolt in the recent months because of joint operations by security forces.

"Many cadres have been arrested or surrendered in recent times. We have also seized a large number of arms and ammunition. We have to see whether this blast has any direct link with the militant groups," he added.

Sniffer dogs and forensic experts have reached the spot and started investigation.

The chief minister condemned the incident and said, "Nobody will be allowed to commit such heinous crimes. Strong action will be taken against those behind this dastardly act."

The blast took place on a day when Sonowal chaired a high-level security review meeting with the top brass of the Home Department and instructed them to ensure a foolproof security cover in Guwahati.

The chief minister also asked the Home Department to strengthen the intelligence gathering system.

Kumar had recently said there was intelligence input about possible attack by ISIS militants in Guwahati city.

The authorities convened a security meeting Thursday with the owners of shopping mall, management committee of the Kamkhya temple and other temples.

Assam Pradesh Congress Committee President Ripun Bora condemned the blast and said attacking common people is a cowardly act by militants.

He also criticised Sonowal, who also holds the Home portfolio, for allegedly failing to provide security to the people of Assam.