A couple involved in a six-hour standoff with a SWAT team in Daly City on Monday pleaded not guilty to gun charges in San Mateo County Superior Court this afternoon.

Daly City resident Joseph Camilleri, 29 and his girlfriend Anna Tostanoski, 25, have each been charged with 12 counts of possession of illegal firearms and one count of firing a gun out of a building, District Attorney Steve Wagstaffe said.

The standoff began at about 5 a.m. after officers who happened to be in the neighborhood heard five shots then saw Camilleri and Tostanoski run into a house on West Market Street, Daly City police Sgt. David Mackriss said.

The pair refused to cooperate when the officers asked to come inside.

SWAT and negotiations teams responded and closed down the area near West Market and Mission streets while authorities established communication with the barricaded couple, who eventually came out and were arrested at about 11:15 a.m.

As many as 20 firearms, including automatic rifles, were found in a search of the home, Wagstaffe said.

Camilleri and Tostanoski remain in custody on $200,000 bail each.

They are scheduled to reappear in court for a preliminary hearing on March 8.