Exxon Mobil Corp. began escorting United Steelworkers (USW) union members from its Beaumont, Texas, complex, a Reuters witness said, as a deadline passed without a new labor contract.

The oil company had set a 10 a.m. (1500 GMT) May 1 deadline to lock out and replace union-represented workers with managers and temporary staff if there were no vote on a company proposal. No vote was taken.

Plant manager Rozena Dendy said in a Facebook post that Exxon Mobil initiated the lockout because of the “real risk of a strike.” Union workers will remain off the job until a contract is reached, she said.

Union officials submitted a last-ditch contract proposal the evening of April 30 that was rejected by the company. The union proposal “would significantly increase costs and limit the company’s ability to safely and efficiently operate,” Exxon Mobil said on its website.

About 30 workers were ushered off the premises by their replacements late April 30. Another 100 began exiting the refinery on May 1, according to a USW official.

“After they gave us a lockout date and time, they could not give up control of the timeline. They had to go early,” Hoot Landry, a USW staff representative, said of the overnight departures. The two sides had given each other a 75-day notice of a strike or lockout, a period ending May 1.

Exxon Mobil said on its website it had offered to negotiate through the night to reach an agreement, but the union wanted to resume talks on May 3.

“We are disappointed negotiations broke down,” Exxon Mobil said. “The lockout will continue until the union accepts the company’s current offer or the parties otherwise reach agreement.”

The company’s April 20 offer “remains on the table,” Exxon Mobil said on its website.