QUITO (Reuters) - At least 17 people died and 12 others were injured in a fire on Friday at a drug rehabilitation clinic in Guayaquil, Ecuador’s largest city, authorities said.

The fire started when patients set mattresses ablaze to try to escape from the clinic, which lacked the necessary permits, according to Tania Varela, the chief of police in the poor area of the city where the incident took place.

Such makeshift treatment centers are common in the Andean country.

“We regret the loss of 17 human lives in this tragedy, and we reject the negligence of the owners,” the Guayaquil fire department said in a statement.

Police are seeking the arrest of the owners and operators of the clinic.