At least 11 bar patrons and a sheriff’s deputy were killed late Wednesday in a shooting at a country and western dance hall in Thousand Oaks, Calif., that was holding an event for college students, officials said.

The gunman is dead, officials said early Thursday, adding that there was no longer a threat to those at the bar, which had been filled with about 100 people at the time of the attack.

The massacre occurred at the Borderline Bar & Grill, with the assailant firing wildly into the crowd.

In addition to the dead, 10 other people may have been injured, according to Sheriff Geoff Dean, who added that it’s too early to know if the shooter took his own life.

The gunman burst into the bar around 11:20 p.m., cloaked in all black.

Ventura County Sheriff’s Department Sgt. Ron Helus and a California Highway Patrol officer entered the bar first and were met with gunfire from the suspect, whose identity was not immediately known. Helus was shot several times and died at an area hospital early Thursday morning, according to Dean.

Helus, a 29-year veteran of the sheriff’s department, was planning to retire next year. Dean said he died "a hero.”

He is survived by a son and his wife, whom he called before entering the bar, Dean said.

"It’s a horrific incident,” Dean said. "It’s part of the horrors that are happening in our country and everywhere, and I think it’s impossible to put any logic or sense to the senseless.

"This community in my 41 years had never experienced anything like this," he added.

Witnesses reported a horrifying scene as gunfire echoed through the club and those inside ran for cover, in some cases using chairs to break windows to escape the building. Others hid in bathrooms and an attic as they frantically called loved ones who were hearing reports of the shooting.

The first 911 calls reporting the shooting were received around 11:20 p.m., according to Dean. Helus and the CHP officer arrived on scene and engaged the suspect by 11:26 p.m., he said.

A motive in the shooting was not immediately clear, but Dean said there was no evidence linking the attack to terrorism. Police believe the weapon used was a handgun.

Eleven victims and the shooter were found dead inside the bar by responding emergency personnel.

"It’s a horrific scene in there,” Dean said. "There’s blood everywhere.”

Teylor Whittler went to Borderline to celebrate her 21st birthday on Wednesday night. She was dancing with friends in the bar when she heard what sounded like firecrackers. She quickly turned and followed the noise, only to find a man holding a gun near the entrance.