A 7.5-magnitude earthquake has rocked the ocean bed near India’s Nicobar Islands, triggering an initial tsunami warning for nearby islands.

The quake occurred on Sunday at 1:26 a.m. local time (1926 GMT) under the Indian Ocean at a depth of 35 kilometers (22 miles) with the epicenter around 160 kilometers west of the Indian archipelago, AFP reported.

The Hawaii-based Pacific Tsunami Warning Center initially issued a warning for the entire Indian Ocean region.

The warning was later downgraded to one for India after the magnitude of the quake was revised to 7.5 from 7.7, and later the center cancelled the alert altogether.

India’s ocean information center issued a “tsunami watch” for
10 to 15 islands, but predicted a mild surge in sea levels of about 50 centimeters (20 inches).

The midnight tremors were felt more than 1,000 kilometers from the epicenter on mainland India, causing some to flee their homes in panic.

Moderate tremors were also felt in the southeastern coastal city of Chennai, but there were no reports of casualties or damage to property.