On Saturday, Airbnb CEO and cofounder Brian Chesky tweeted that the company would be banning “party houses” after five people died in a shooting during a 100-plus person Halloween party at an Airbnb rental in Orinda, California.

Chesky outlines the steps Airbnb is taking in the same Twitter thread, including creating a rapid response team for “party houses”, presumably to help homeowners prevent dangerous parties. Chesky did not explain what a “party house” is in the thread. Airbnb spokesperson Ben Breit defined “party houses” as rentals which repeatedly disturb neighbors, according to The Washington Post, but said that any specific standards have yet to be determined.

Airbnb claims it already uses an automated risk detection system that uses “predictive analytics and machine learning to instantly evaluate hundreds of signals that help us flag and investigate suspicious activity before it happens,” and Chesky says the company will have more humans screening that system soon too:

First, we are expanding manual screening of high-risk reservations flagged by our risk detection technology. — Brian Chesky (@bchesky) November 2, 2019

But it’s unclear whether that system, or the background checks and watchlists that Airbnb also claims it uses to spot potential bad actors, would have prevented this particular renter from throwing the party that led to the deadly shooting.

The owners of the site of the shooting, Wenlin Luo and Michael Young Wang, were apparently worried about a party themselves — Wang was suspicious when a woman requested to rent the four-bedroom house for one night on Halloween, and explicitly reminded her that no parties were allowed before agreeing to let her rent the house, a source told the Associated Press. But the owners apparently didn’t stop her from renting it, after she told them her dozen family members needed to escape the smoke from the wildfire in Sonoma County because they had asthma, the source said.

Instead, over 100 people came to the house to attend what was advertised on social media as an “Airbnb mansion party.”

Wang said his wife contacted the renter on Thursday after neighbors told them about the party, according to the Associated Press. The renter claimed that only a dozen people were at the house, even though Wang said he could see more people from his doorbell camera’s video feed.

Neighbors made noise complaints around 9:19 PM and 10:25 PM, Reuters reports, with an officer dispatched to investigate the complaints around 10:48 PM and gunfire starting around 10:50 PM. Three people died at the scene and two died later at a hospital, according to The Los Angeles Times. As of Monday, police are still investigating and haven’t identified any suspects or made any arrests.

The Orinda house had received several complaints since it was listed as a short-term rental last November, including one about a party in February, CBS News reports.

The house has been taken off of Airbnb and the woman who rented it during the party has been banned from Airbnb as well.