Airbnb’s C.E.O Brian Chesky has vowed that the platform will conduct a comprehensive review of every property listed to improve trust.

At the DealBook Conference on Wednesday, Chesky promised Airbnb guests “peace of mind,” after five people were killed at a party in an Airbnb rental house in Northern California on Oct. 31.

Chesky said that the company would also conduct rigorous reviews of “high-risk” reservations, open a hotline for concerned neighbours and put in place new guarantees for dissatisfied customers.

Five people were killed and several others injured in a mass shooting at a Halloween party at an Airbnb rental attended by college students in Orinda, northern California. The shooting took place around 10:50 p.m. local time. When the officers arrived, they found more than 100 people at a house party, including gunshot victims, injured party-goers, and numerous people fleeing the scene.

The owner of the Airbnb, Michael Wang, told the San Francisco Chronicle that he rented the house to a woman on Airbnb, who told him she was having a family reunion and that only 12 people would be at the house.

In a statement sent to TIME, Airbnb said that the party was unauthorized and the guest who booked the house would be banned from the platform.