Boeing’s engine testing extended past midnight, and King County’s airport got noise complaints from neighbors.

Late-night testing of the Boeing 777X engine Tuesday drew “numerous” noise complaints and violated airport policy, according to King County.

The aerospace giant was approved to perform engine run-up testing between 6 and 9 p.m., but Boeing didn’t begin testing until 9:30 p.m., according to a statement released Thursday from King County International Airport. The testing continued until 12:30 a.m. when airport operations staff contacted Boeing.

The airport says the testing also violated King County International Airport’s noise abatement policy, which restricts when certain activities can take place.

Boeing told the county in a statement that the testing extended beyond the agreed time, and it apologized for disrupting residents.

“This was not a normal occurrence and we are making adjustments to prevent it from happening in the future,” the statement read in part.

Engine run-up testing of the 777X has been put on hold, and King County says it contacted Boeing leadership to ensure the incident won’t happen again.