Police convoy attacked by gunmen with rocket-propelled grenades in Punjab province in area known to have criminal hideouts.

Gunmen armed with rocket-propelled grenades have ambushed a police convoy in eastern Pakistan’s Punjab province, killing at least 11 officers and wounding seven, authorities say.

No one immediately claimed responsibility for the attack in the Rahim Yar Khan district’s Kacha town on Thursday.

The officers were ambushed while on patrol in a deserted area in search of robbers who operate in the region. Police said the gunmen were likely robbers and not members of an armed group.

“The bandits attacked the vehicles with rocket launchers after one of the vehicles in the convoy broke down,” said a statement from the inspector general’s office in Punjab.

Security forces often carry out operations against bandits in Punjab and Sindh province in the south. They hide in rural, forested areas and sometimes carry out kidnappings to make money through ransoms. They have also killed several police officers in attacks over recent months.

Kacha is known for robbers’ hideouts along the Indus River, where hundreds of heavily armed bandits evade police.

Police said one of the police vehicles apparently broke down while passing through accumulated rainwater along farm fields when dozens of bandits launched the attack, one of the deadliest of its kind in recent years.

Prime Minister Shehbaz Sharif released a statement calling for “immediate and effective action” against those responsible.

Pakistan has witnessed a surge in attacks by armed groups in recent years, but such a high number of police casualties in a single attack is rare.

Earlier on Thursday, gunmen opened fire on a school van in Punjab, killing two children and wounding six people, police said. No one claimed responsibility for that attack.

A local police official told The Associated Press the attack appeared to target the driver of the bus and the motive was likely one of “enmity”.

Pakistan’s government has struggled for decades to subdue armed groups that  operate in a number of provinces throughout the country. Some are criminal organisations while others, such as Tehreek-e-Taliban Pakistan, also known as the Pakistan Taliban, aim to depose the government.