Airbnb has said it's banning "party houses" after five people were killed at a Halloween party in California.
The home rental service said it will take steps to "combat unauthorised parties and get rid of abusive host and guest conduct".
There were said to be around 100 people at the Halloween party on October 31 in Orinda.
One attendee said he was enjoying the music and watching others dancing when he heard shots and people started running.
The screaming seemed to last forever, said Devan, who asked that his last name not be used because he feared for his safety.
"Everybody started running, scrambling," he said.
"People were just collapsing and friends were helping friends, it was a scary situation and then as everyone is panicking and stuff, there were more shots," he added.
The homeowner said was suspicious of a one-night rental on Halloween and reminded the renter that no parties were allowed beforehand.
The owner, Michael Wang, said his wife reached out to the renter Thursday night after neighbours 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 neighbour already sent us a message saying there was a shooting," he told the Chronicle.
Two guns were found at the property and no arrests have been made, US authorities confirmed.
In a series of tweets the CEO of the company, Brian Chesky, said Airbnb is expanding manual screening of "high risk" reservations and will remove guests who fail to comply with policies banning parties at rental homes.
He also said the company is forming a "rapid response team" when complaints of unauthorised parties come in.
"We must do better, and we will. This is unacceptable," he tweeted.