Thousands of Chrysler LLC autoworkers started to walk off the job Wednesday after the automaker and the United Auto Workers union failed to settle on a tentative contract agreement before a union-imposed deadline.

It would be the first UAW strike against Chrysler since 1997, when one plant was shut down for a month, and the first strike against Chrysler during contract talks since 1985. There was no immediate official word from the union or Chrysler on whether it was a nationwide strike.

In Indiana, Chrysler operates three transmission plants and a casting factory, all in Kokomo, that have about 6,000 workers.

The UAW, which must reach new four-year agreements with all three Detroit automakers, struck General Motors Corp. for two days before agreeing on a tentative pact with the automaker on Set. 26. The union hasn't yet settled with Ford Motor Co.