Two No. 6 subway cars derailed overnight in lower Manhattan, causing massive delays during the morning commute.

NYC Transit said the derailment occurred at 3:52 a.m. on a northbound train between the Brooklyn Bridge and Canal Street stations.

Service was restored at 9:02 a.m., officials said.

The agency said an empty train backed up to the disabled train and 19 people were safely evacuated.

No one was injured.

The cause remains under investigation.