HAYWARD -- About 500 union workers went on strike Monday at transit bus maker Gillig Corp.'s Hayward plant, where one man was arrested for trying to block a truck driver from crossing a picket line.

Contract negotiations have been ongoing for about two months. The workers are seeking increased wages and increased company contributions for rising health care costs.

About 440 workers represented by Teamsters Local 853 and another 60 workers represented by the Painters Local 1176 struck at the plant on Clawiter Road at 5 a.m. After striking workers blocked the truck driver from entering the facility, he got out of his truck and a fight started about 6:30 a.m., but broke up before Hayward police arrived, police Lt. Reid Lindblom said.

Interviews with the driver and others still on the scene led to the arrest of Wayne Overson, 54, of Union City, on suspicion of making criminal threats, battery and vandalism.

Teamsters Local 853's principal officer Rome Aloise called it a trumped-up incident. "Sometimes you'll see a company do things to exacerbate a situation," he said. "We preach being peaceful and picketing peacefully. We're chalking this up to over-exuberance by a few people."

Gillig is one of the top producers of transit buses in North America and one of the the only remaining American bus makers that builds buses from the ground up. The company produces about 25 public transit buses a week for cities across the country.