HOUSTON (AP) A United Airlines jet bound for Boston had engine trouble and safely returned to Houston.

A United spokesman says Flight 1124 carried 146 passengers and a crew of six when it took off Sunday from George Bush Intercontinental Airport. The Boeing 737 had mechanical problem with an engine and returned to Houston.

Spokesman Joe Micucci (muh-KOO'-chee) said Monday that United is conducting a thorough review to determine what caused the engine issue.

Passengers were put on another plane Sunday afternoon and continued on to Boston.