GALVESTON, Texas (AP) — Hundreds of thousands of dead fish have washed up on the beach in a tourist-popular Southeast Texas city.

Officials in Galveston say cleanup crews planned to work Monday to remove the dead fish.

Peter Davis with the Galveston Island Beach Patrol said Sunday that the small shad fish likely were killed by low oxygen levels in the Gulf of Mexico. Davis estimated hundreds of thousands of fish have died.

Galveston County health officials say the water is fine for beach goers.

Biologist Steven Mitchell with the Texas Parks and Wildlife Department says calm conditions and summer heat may have contributed to the fish kill. He says there's a possibility of a dead zone in the water off Galveston. Testing is expected this week.