ISLAMABAD, June 18 (Xinhua) -- At least five people were killed and several others injured after two groups clashed inside a hospital in Nankana Sahib district of Pakistan's eastern Punjab province, local media reported Tuesday.

According to the reports, the groups that from two different clans opened fire at each other late Monday over some petty dispute in the emergency section of the District Headquarters Hospital Nankana Sahib, killing four people on the spot while injuring several others.

One of the injured succumbed to his injuries at a private hospital in the district, police said.

Following the incident, heavy contingent of police rushed to the hospital, where a state of emergency has been imposed.

According to hospital sources, at least three people among the injured were in critical condition.

During the firing incident, all medical attendants, patients and doctors fled the facility to seek refuge, police said, adding that the attackers managed to run away from the scene, and a search operation is underway.