Members of the International Association of Machinists and Aerospace Workers went on strike Monday at jet engine maker Pratt & Whitney in Connecticut, as negotiations over wages, retirement benefits and job security broke down.

Unionized machinists voted down the company’s latest proposed contract at a meeting Sunday and began striking Monday.

More than 3,000 Pratt & Whitney employees voted to go on strike after unresolved issues in contract negotiations with the aerospace manufacturer. A union official said the plan was to go on strike at 12:01 a.