MONTERREY, Mexico (AP) - The offices of a major Mexican newspaper came under attack Sunday for the third time this month.

Several masked, armed men broke into a branch office of the El Norte newspaper near the northern city of Monterrey, poured out gasoline and ignited it. The newspaper's website said none of the 15 people working in the Sierra Madre office were injured. Firefighters in the municipality of San Pedro Garza Garcia quickly extinguished the blaze.

Monterrey-based El Norte is part of the Reforma Group which publishes newspapers around the country. The office attacked Sunday puts together a weekly society insert covering weddings, parties and the doings of local celebrities.

Police said the attackers fled without being captured, and the newspaper said no gang has claimed responsibility for the attack but drug cartels have increasingly targeted Mexican newspapers to discourage coverage of drug violence.

Two other outlying offices of the paper were attacked with grenades and gunfire on July 10.