AZUSA — A Fontana woman died instantly Wednesday when her vehicle struck a pillar, police said.

Theresa Tonner, 54, was killed in the 8:37 a.m. crash on First Street, near the 210 Freeway, Azusa police Cpl. Dean Brewer said in a written statement.

No other vehicles or pedestrians were involved in the crash, police said, and witnesses indicated that Tonner’s Subaru Outback may have been speeding prior to the impact.

The cause of the crash remained under investigation.