ORINDA, California - Airbnb says it will take action to prevent unauthorized parties in the wake of a deadly shooting at a Halloween party held at an Airbnb rental home in northern California.

"What happened on Thursday night in Orinda, California was horrible. I feel for the families and neighbors impacted by this tragedy," Airbnb CEO Brian Chesky said.

In a series of tweets, Chesky also said on Saturday the San Francisco-based company is expanding manual screening of "high risk "reservations and will remove guests who fail to comply with policies banning parties at Airbnb rentals.

He also said the company is forming a "rapid response team "when it receives complaints of unauthorized.

"We must do better, and we will. This is unacceptable," he tweeted.

Five people died after a Thursday night shooting that sent about 100 terrified partygoers running for their lives in the San Francisco suburb of Orinda.

The four-bedroom home had been rented on Airbnb by a woman who told the owner her dozen family members had asthma and needed to escape smoke from a wildfire, the person with knowledge of the transaction told The Associated Press. A fire burning in Sonoma County about 97 kilometers north of Orinda earlier in the week fouled the air over a wide area.

The house owner, Michael Wang, said his wife contacted the renter on Thursday night after neighbors contacted them about the party. The renter said there were only a dozen people at the home but Wang said he could see more people on video from his doorbell camera.

"We called the police. They were on the way to go there to stop them, but before we got there the neighbor already sent us a message saying there was a shooting," he said.

The couple was suspicious of a one-night rental on Thursday, Oct 31, the Halloween holiday. Before agreeing, they reminded the renter that no parties were allowed, said a person with knowledge of the transaction, who spoke on condition of anonymity.

No arrests had been made and there was no immediate word on a motive for the attack. Two guns were found at the property, authorities said.

AP - Xinhua