At least four people died and ten people were injured Thursday in a strong explosion in the quarters of the Intervention and Rescue Group (GIR), a specialized police unit in northern Quito, The Interior Ministry said.The explosion happened near 11:00 local time (1600 GMT), during a practice on the use of explosives in the GIR training center, located in Pusuqui, in northwest Quito.The Interior Ministry said the injured people were taken to hospitals in the northern zone of the Ecuadorian capital.The detonation was heard around a one-kilometer radius and burned a large part of the sides of a near hill.The accident caused panic among the neighbors of the police quarter, as well as a large traffic jam around the zone.