RODEO (CBS SF) – Flaring at a refinery in the East Bay late Monday night was visible for miles and prompted many calls to the fire department.

Contra Costa County health officials told KPIX 5 that there was an “unplanned shutdown” at the Phillips Refinery around 10:25 p.m. Monday night. It is unclear what caused the shutdown.

Officials said the shutdown triggered the release of hydrogen gas and the flaring.

Witnesses in the East Bay and Solano County reported seeing a fireball in the night sky.

The fire department said the flaring of hydrogen gas does not pose a danger to the community. Flaring is expected to continue into the early morning hours Tuesday.