Brazilian police have been fighting with drug gangs in slums near the center of Rio de Janeiro, with shots shattering windows in the mayor's office.

A TV network's helicopter has been hit and forced to make an emergency landing.

There are no immediate reports of deaths.

Police say about 120 officers were met with gunfire when they entered the slums early Monday to search for gang leaders.

According to a government statement, shots knocked out windows in the office of Mayor Eduardo Paes. He was in the building, but is unhurt.

Globo TV's website says one of its helicopters was hit by three bullets. Nobody was hurt, but the pilot was forced to make an emergency landing.