Christopher Heffner, public relations manager for Mack Trucks, Lower Macungie Township, has told the Lehigh Valley Press 400 workers from its Mack Lehigh Valley manufacturing location will be laid off.

Heffner told The Press on Dec. 15 a general announcement was made to staff this morning.

“We regret having to take this action,” Heffner said.

The Lower Macungie facility recently celebrated its 40th year of manufacturing the iconic Mack truck.