Texas Parks and Wildlife Department officials say that state game wardens have discovered up to 3,000 dead sharks tangled in a long stretch of fishing net off the Texas coast near southern South Padre Island.

“About 3 miles of gill net was removed just past the third sandbar near the mouth of the Rio Grande,” the department said in a statement. “The nets were running north and south, catching anything that attempted to get into shallow water.”

Sergeant James Dunks told a local tv station that “an unbelievable amount of sharks, anywhere between two and three thousand black tips, bonnet heads and sharp nose sharks” were killed. Authorities suspect Mexican fishermen set the illegal nets, but no arrests have been made.