MEXICO CITY (AP) _ Mexico’s public health system has suspended infant vaccines and mounted an investigation after two babies died and 29 were sickened in an impoverished community in southern Mexico.

The Mexican Institute for Social Security says six of the 29 babies are in grave condition after receiving vaccinations for tuberculosis, rotovirus and Hepatitis B. The cause of the adverse reactions is not known, the institute said Sunday.

The institute said it stopped vaccines nationwide on Saturday as a precaution.

Rev. Marcelo Perez, a Roman Catholic priest, told The Associated Press that families of the babies said they became sick within hours. The adverse reactions started Friday and the babies were taken to a hospital in Simojovel, Chiapas, where 93 percent of the people live in poverty, according to government statistics.