DALLAS (AP) — Dallas officials are trying to determine what caused the city's emergency sirens to go off in the night.

The sirens began sounding late Friday night. Officials said there was no emergency and they were trying to determine what caused the malfunction.

City spokeswoman Sana Syed said the sirens started at 11:40 p.m. Friday and the system was completely shut off by 1:20 p.m. Saturday.

Officials say fire dispatch crews had to manually shut off the sirens. The city's website says there are 156 outdoor warning sirens placed throughout the city.

Officials say there was a surge in calls to 911 when the sirens were going off. The longest wait time was two minutes.

Police in the suburb of Garland said their sirens also went off in error.