SAN FRANCISCO — Federal authorities have arrested a man they say intended to detonate a car bomb in front of a Northern California bank.

The U.S. Department of Justice announced Friday that authorities had arrested 28-year-old Matthew Aaron Llaneza on Thursday night following a multi-month sting operation in which an undercover FBI agent helped Llaneza build an explosive that the agent secretly rendered inoperable.

The FBI said it had been tracking Llaneza for months and arrested him after he tried to set off the bomb with a cellphone in front of a Bank of America branch in Oakland.

The FBI said Llaneza hoped to spark a civil war by making the bomb blast appear to be the work of anti-government “militias.”