Four people were killed and several others were wounded in a shooting at a Halloween party at a rental home near San Francisco, local authorities said. The shooting Thursday night took place at a rented Airbnb home in Orinda, around 18 miles (30 km) northeast of San Francisco, where more than 100 people were attending a "mansion party" advertised on social media.

Michael Wang, the home owner, told the local CBS station that he rented his house to a woman who said she was organizing a family reunion for a dozen people. The Contra Costa County Sheriff's office said officers responding to reports of a shooting arrived at the house at about 10:50 pm and found three people dead at the scene. A fourth person died later at the hospital.

It was unclear what prompted the violence. "It's a very somber day here in Orinda," mayor Inga Miller told local radio. Earlier in the week three men were killed and nine others wounded at a Halloween party in Long Beach, south of Los Angeles. Police said the three men were standing in the backyard of the house Tuesday evening when someone opened fire from an alley.