The first 7.2-magnitude earthquake was followed less than a minute later by a 7.5-magnitude earthquake, according to U.S. monitoring agencies. The epicenter was near San Felipe, a city of about 220,000 in the state of Yaracuy, about 200 miles west of Caracas. The temblors happened shortly after 6 p.m. local time.

As seismologists review available data, they may revise the reported magnitudes of the earthquakes.

Videos on social media showed passengers running for safety inside the international airport in Maiquetía, near Caracas. Other images showed rescue teams combing through collapsed structures in Caracas searching for survivors.

Venezuela’s government said on state television that a “strong earthquake” was felt in Caracas and several parts of the country, but that the extent of the damage was not immediately clear.

Venezuelan authorities did not immediately respond to requests for further comment. Officials at the United States Embassy in Caracas also did not immediately respond.

• People in the affected region largely reside in structures that are vulnerable to earthquake shaking, though resistant structures exist, according to the U.S.G.S. The main vulnerable buildings are made of unreinforced brick masonry and adobe block construction, the service said.

• A seismologist with the U.S.G.S., Paul Earle, called the earthquakes “devastating” and said the agency’s models estimated “potentially over 1,000 fatalities to potentially tens of thousands.”

• Although the quakes struck on land, the U.S. Pacific Tsunami Warning Center briefly issued tsunami warnings along the coasts of Venezuela, Bonaire and Curaçao and Aruba.

Reporting was contributed by Amy Graff, Isayen Herrera and Tibisay Romero.