The crumbling buildings and chaos in Mexico City is a sight Dave Marquez knows all too well. He's a firefighter by trade, but off the clock, he's a volunteer first-responder with Reach Out Worldwide.
Hurricane Harvey was his last trip, and an earthquake in Haiti was one of his toughest assignments.
"There were a lot of orphaned children that we treated. A lot of people who had just had limbs recently amputated with no pain medication to help them out. And no hope of any relief," he said.
For emergency personnel on their way to the destruction, many obstacles lie ahead. Marquez anticipates groups coming from out of the country will get stuck in customs before they can step foot on Mexican soil.
"They're dealing with things like road closures, just the confusion of being able to assemble themselves. Trying to figure out where they're going to go, trying to assemble the resources to get there, like vehicles, like fuel," Marquez said.
Videos out of Mexico show neighbors trying to get victims out of the rubble. Marquez said it's these first 24 to 48 hours that are critical for life-saving efforts.
"One of the big things you think about in these situations, is how long someone can survive without water, especially if they're entombed somewhere or completely outside of receiving supplies," he said.
Reach Out Worldwide is sending a team to Puerto Rico this weekend and are stretched too thin to commit to going to Mexico. But Marquez said they are always looking for volunteers.