THOUSAND OAKS, Calif. (AP) - Ventura County Sheriff Geoff Dean says the gunman who killed 12 people at a Southern California bar used a pistol.

A forensics team works the scene Thursday, Nov. 8, 2018, in Thousand Oaks, Calif. where a gunman opened fire Wednesday inside a country dance bar. (Photo: AP)

Dean says 28-year-old Ian David Long was armed with a Glock 21, a .45-caliber handgun designed to hold 10 rounds plus one in the chamber.

But the sheriff says the gun had an extended magazine that is illegal in California. The sheriff says he does not know how many rounds that magazine can hold.

The gunman attacked staff and patrons at Borderline Bar and Grill in Thousand Oaks late Wednesday.

The bar west of Los Angeles was holding a weekly country music dance night that attracts area college students.

One of those killed was sheriff's Sgt. Ron Helus, who was cut down when he tried to enter the club with Highway Patrol officers responding to the gunfire. The others killed have not been identified.

One other person suffered a gunshot wound and as many as 15 others suffered minor injuries from jumping out windows and diving under tables.