Sacramento firefighters responded to a fire alarm at the federal courthouse downtown Wednesday afternoon.

Steps are being taken to fix the problem after a faulty detector or possibly a bad ballast inside a light fixture set off a fifth-floor fire alarm at the Robert T. Matsui Federal Courthouse, 501 I St., said Fire Department Station 2 Capt. Scott Visser.

The alarm was reported at 1:58 p.m. Four fire stations -- 1, 2, 13 and 14 -- sent 13 firefighters, three engines and one truck to the scene.