EXCLUSIVE

"2 Broke Girls" star Beth Behrs was viciously attacked by her neighbor's dog Wednesday ... so say people in her L.A. building ... and the actress even called Animal Control to handle the situation.

Luckily, Behrs wasn't injured in the attack ... but we're told the neighbor's pit bull mix did bite off a chunk of her sweater.

Here's what happened ... building sources tell us, Behrs was with her Yorkie Betty when a neighbor approached while walking a large brown lab and a pit bull mix. It's unclear why, but we're told the pit reared up and attacked Behrs, tearing a chunk off her sweater.

We're told Behrs was extremely upset by the attack and immediately called Animal Control, which eventually responded to the scene. Sources say the neighbor was fined as a result of the incident, and has been instructed to keep the dogs under better control.