WASHINGTON — Police briefly evacuated hundreds of workers and tourists from the U.S. Capitol and its adjacent visitors’ center on Tuesday in a problem officials tentatively blamed on a faulty exhaust fan in a visitor center kitchen.

Within an hour after alarms sounded, employees returned to the building. Tourists were readmitted shortly after that.

Lawmakers are in recess this week for the weeklong Memorial Day break.

The U.S. Capitol Police told congressional workers in an email that two alarms were triggered in the visitors’ center, which they said was apparently caused by “a known problem with environmental controls with the kitchen exhaust fan.” It provided no additional detail.

An email sent later to House staff by the chamber’s sergeant at arms office said the triggering of alarms “was most likely caused by smoke in the kitchen; there was no fire.”

The evacuation occurred two days after a bomb squad destroyed a pressure cooker found in an unattended, “suspicious” vehicle on the National Mall near the Capitol and the vehicle’s Virginia owner was arrested.