The pair are not being identified until their relatives are notified. In all, the volume of the rockfalls weighed about 1,300 tons, and the irregular sheet of rock that fell was estimated to be 130 feet tall, 65 feet wide and 3 to 10 feet thick.
Yosemite remained open after Wednesday's rock fall, and other activities throughout the park weren't affected, rangers said.
Yosemite Valley and the park records about 80 rockfalls per year - though many more rockfalls go unreported, officials said.
Locals ask for help for their family in Puerto Rico
Homeland Security Adviser Tom Bossert said 10,000 federal forces are on the island, including 7,200 troops. "I cry everyday. Millions of people are still without water and power one week after the powerful storm tore through the island.
Zabrok described the first and largest rock fall he saw: "I saw a ..."
Mountaineers from around the world travel to the park in the Sierra Nevada to scale El Capitan's sheer face. He says the rock was the size of five houses. "We were on the summit of Half Dome when we saw this".
Canadian climber Peter Zabrok, 57, was scaling El Capitan and was above the rockfall when it occurred, he told Fox News. It was unclear if any of the approximately 30 climbers on the rock, or park tourists below, was injured, the Los Angeles Times reported.
The rocks appeared to have fallen from an area near the popular "Waterfall Route" climbing trail during an active time for hiking in the popular national park. He said no further details were immediately available. Rescue workers evacuated the victims from the scene. "100-foot by 100-foot chunk of granite the size of an apartment building peel off 2,000 feet above the deck, hit the wall 1,000 feet up and shatter into a hundred thousand pieces that completely annihilated everything".