The National Transportation Safety Board has revealed more details about a grisly bus explosion that killed 23 people last year. The accident occurred as residents and staff from an assisted living facility were being evacuated from Hurricane Rita.

Interviews with employees of Sunrise Senior Living Inc.’s facility near Houston depict a chaotic scene in which employees tried to evacuate the 38 seniors — many in their 80s and 90s — from a bus that caught fire. A total of 23 residents of the Brighton Gardens community in Bellaire, TX, died.

State and federal officials say the chartered vehicle had a defective brake and faulty wheel bearings, as well as an illegal license plate. Nor did the vehicle’s driver have a valid license. Sunrise chartered the coach from BusBank, a Chicago broker that contracted with a south Texas bus operator called Global Limo, Inc.

Eight lawsuits have been filed naming Global Limo and BusBank. Six of the eight lawsuits also name Sunrise, asserting it was negligent in hiring Global Limo. Sunrise, the largest assisted living company in the United States, has denied the allegations. The NTSB has not determined the initial cause of the fire.