Hurricane Agatha triggered flooding and landslides in Mexico, killing at least 11 people and leaving 20 missing, the governor of the southern state of Oaxaca said, AP reported.

"There were fundamentally two reasons," Governor Alejandro Murat said.

"There were rivers that overflowed, and on the other hand, and the most serious part, were landslides."

Murat said the deaths appeared to be concentrated in several small mountain towns near the coast. But there were also reports of three children missing near the resort of Huatulco.

Agatha went down in history as the strongest hurricane ever recorded, making landfall in May during the East Pacific hurricane season.