HELENA, Mont. (AP) — Federal agents say a weekend search of a south-central Montana residence that turned up homemade bombs was connected to a bank robbery investigation.

FBI Los Angeles spokeswoman Laura Eimiller says numerous agencies were investigating whether evidence found in the search in Roundup, Montana, was connected to a series of bank robberies in California, Washington state, Idaho and Nebraska.

In 2012 and 2014, a man the FBI called “the AK-47 bandit” robbed several banks. The robber shot and wounded a police officer in Chino, California.

Officials with the Musselshell County sheriff’s office in Montana say the weekend search was linked to 39-year-old Richard Gathercole, who was arrested last week in Nebraska. He was wanted after someone fired shots at a Kansas trooper. The trooper wasn’t injured.

Officials did not say how Gathercole was connected to the residence where the bombs were found.