LAHORE, Pakistan (Reuters) - An explosion near the Punjab provincial assembly in the Pakistani city of Lahore killed at least 13 people and wounded 83 others on Monday, a senior police official said.

Police and rescue workers work at the scene of a blast in Lahore, Pakistan February 13, 2017. REUTERS/Stringer

Mushtaq Sukhera, inspector general of police in Punjab province, said five police officers were among the dead when an explosion rocked a protest organized by Pakistan’s chemists and pharmaceuticals manufacturers.

“It was a suicide attack. The bomber exploded himself when successful negotiations were underway between police officials and the protesters,” Sukhera told reporters.

A spokesman for Jamaat-ur-Ahrar, a faction of the Pakistani Taliban, called Reuters and claimed responsibility.

The militant group also warned the Lahore attack was the start of a new campaign against government departments. “You are on our target across the country,” it added in a statement.

Jamaat-ur-Ahrar had also claimed responsibility for an Easter Day bombing in Lahore last year that killed more than 70 people in a public park.

Security in Pakistan has vastly improved in recent years but Islamist groups such as the Pakistani Taliban and Islamic State still pose a threat and have carried out mass attacks.

Prime Minister Nawaz Sharif said the attacks will not weaken Pakistan’s resolve in fight against militancy.

“We have fought this fight against the terrorists among us, and will continue to fight it until we liberate our people of this cancer, and avenge those who have laid down their lives for us,” he said in a statement.

The latest blast may jeopardize plans by Pakistan, a cricket-obsessed nation, to host the final of its domestic Twenty20 tournament on home soil in Lahore in March.

For years, Pakistan’s international test cricket matches have been played abroad and the current Twenty20 tournament is being played in United Arab Emirates due to security fears.