A police constable opened fire in the King George's Medical University (KGMU) here and critically injured four of his family, an officer said Tuesday.

The firing occurred Monday night in residential area of the university campus when Shivjeet Singh, guard to the additional director general of police, opened fire from his service revolver, injuring his wife, brother-in-law and two other relatives, police said.

The constable was living separately from his wife Neetu, who had complained to police that he was demanding dowry and harrassing her. Annoyed over this, Shivjeet Singh opened fire at her and others when they were returning home from a wedding, police said.

The injured were identified as Neetu (31), Anil Singh (28), Maya (40) and Saroj Singh (50). Anil Singh's condition is stated to be critical, police said.

Police official Sarvesh Mishra said the constable was arrested and is being questioned.