Authorities closed schools and suspended internet services in a northern Indian city on Monday, officials said, a day after four people were killed in clashes sparked by an official survey probing whether a 16th-century mosque was built on a Hindu temple.

Two days after deadly violence in Sambhal left four people dead and many others injured, the city in India’s northern state of Uttar Pradesh remains gripped by tension. The violence broke out on Sunday during a court-ordered survey of the centuries-old Shahi Jama Masjid (mosque) that some Hindu groups claim was built at the site of a destroyed temple.

Tensions have reached a boiling point in Northern India, where a centuries-old mosque has sparked deadly clashes between protestors and police.

Clashes broke out between protesters and the police during a court-monitored survey of the Mughal-era Jama Masjid (mosque). Authorities have detained 21 people in connection with