Police in Pakistan say Shiite Muslims staging a religious procession beat three Sunnis to death after the two sides clashed.

Police officer Afzal Hussain says 15 people, mostly police officers, were wounded in the clash Friday in the city of Rawalpindi, located near the capital, Islamabad.

Hussain says the Sunnis killed were members of an Islamic seminary. The Sunnis were pulled out of the seminary and beaten to death after members of the school shouted insults at the Shiites as they passed.

The Shiites also set several shops outside the seminary on fire. The army eventually reached the scene and took control.

The Shiites were observing Ashoura, which commemorates the 7th century death of the Prophet Muhammad's grandson. The schism between Sunnis and Shiites dates back to that time.