MADRID (AP) — Nearly 40 migrants have ended an overnight protest on the rooftop of a detention center in Spain's capital.

The migrants, most reported to be from Algeria, shouted for "Freedom" and "Dignity" during the protest, which began late Tuesday.

Police cordoned off the area around the center on Madrid's outskirts, but the protest finished peacefully early Wednesday following negotiations with officials.

Spain has nine detention centers that are used to hold migrants considered to be in the country illegally.

Rights groups have long criticized the centers, saying migrants live in prison-like conditions, and have called for their closure.