SAN DIEGO -- A fight on the sand in Pacific Beach escalated into a full-scale brawl Monday, with bottles and cans thrown at police officers -- who were pushed back -- but returned in riot gear to quell the crowd.

The fight broke out about 5 p.m. at the foot of Reed Avenue when partiers refused police orders to put away a water slide, according to broadcast reports.

Police responded with smoke bombs and mace when the bottles and cans were thrown, according to the reports.

A police dog bit one person, according to a San Diego police dispatcher.

Police arrested at least 16 people.

"It was a really bad situation,'' one witness said.

Another witness says one woman fired a paintball gun at police.

Forty officers in riot gear with dogs were called in, along with the police helicopter ABLE to observe the situation from the air. Beachgoers were encouraged to go home, the reports said.