NASCAR is updating its fire safety requirements for race teams in the wake of an explosive accident on pit road at Richmond.

Three crew members were injured in a fire that erupted during a pit stop in last month's Xfinity Series race. Fuel spilled as the crew was servicing Brendan Gaughan's car and a spark ignited the blaze.

NASCAR senior vice president Robin Pemberton said Friday the Richmond fire was caused when a fastener bolt failed on the gas can.

NASCAR will now mandate all over-the-wall pit crew members wear fire-protective underwear, socks, head socks and gloves. All previously were recommended for over-the-wall pit crew members other than the gas man.

The mandate takes effect June 4, except for the socks, which must be SFI-certified by August.