JUCHITÁN DE ZARAGOZA, Mexico — Concepción Rueda Gomes has been collecting food and supplies since Mexico’s strongest earthquake in living memory struck her hometown, Juchitán, last week. But when it came time to distributing the aid she turned to private agencies for help.

“There was no way I was going to give away the help we raised to some local official or leader so he can just hand them out to his friends and family,” Ms. Rueda, 50, a jewelry designer, said at her home in Juchitán, where volunteers were loading up three trucks with food, water and blankets.

As the death toll in the earthquake rose to 96 on Monday, desperation intensified among people who have spent four nights on the streets in front of damaged homes. Although the Mexican army has been handing out supplies in the worst-hit regions of southern Oaxaca State, even Gov. Alejandro Murat admitted that help had yet to arrive for many people.

“We are talking about almost a million people who need attention block by block,” he said in a television interview.