A 7.3 magnitude earthquake struck in the Pacific Ocean off El Salvador late on Sunday, triggering a brief tsunami warning along a stretch of the central American coast but causing no major damage or casualties, early reports indicated.

The quake hit about 74 miles offshore at a depth of just over 20 km (12 miles), the U.S. Geological Survey said. It earlier gave the magnitude as 7.4.

A small tsunami hit the El Salvador port of Acajutla following the quake, the Pacific Tsunami Warning Center said.

It issued and then cancelled a tsunami alert for El Salvador, Costa Rica, Nicaragua, Honduras, Guatemala, Panama and Mexico.

Emergency services in El Salvador and Guatemala said the quake had caused no discernible damage, and there were no early reports of damage or casualties from elsewhere in the region.

In the El Salvador capital San Salvador, several residents reached by phone very early on Monday morning said they had not felt the quake.

There were no immediate reports of damage to shipping.