The bodies of 24 men, believed to be illegal migrants, have been washed ashore in the Mexican state of Oaxaca after their boat capsized on Saturday, BBC reported.
The victims were thought to have come from Central America, trying to get to the US.
Rescue operation is still under way as local authorities suspect many more people may be in the water.
At this stage, rough weather is being blamed, but boats carrying illegal immigrants through Mexican waters are often overloaded or unseaworthy.
Often people are carried first to Mexico by boat, from where they must make a second hazardous journey across the border hidden in trucks.
Other journeys involve hundreds of kilometres by sea to take immigrants directly to the US coastline.