WEST CHICAGO, Ill. — Classes are back on for about 4,000 students in West Chicago after a tentative agreement ended a teachers strike in the Chicago suburb.

Officials with West Chicago Elementary District 33 started calling parents overnight to let them know that classes would resume Thursday after a three-day strike.

About 280 teachers began the walkout Monday after more than 17 months of negotiations failed to reach an agreement. The district includes six elementary schools, a preschool and a middle school.

Negotiators aren't yet disclosing details of the tentative agreement. They reached the deal early Thursday after nearly 12 hours of talks with a federal mediator. Salaries and health insurance costs were among the main sticking points.