A magnitude 7.2 earthquake hit about 160km west of Caracas on Wednesday evening, followed 39 seconds later by a magnitude 7.5 tremor, according to the US Geological Survey.
Emergency workers have already pulled dozens of people alive from the rubble, including two injured toddlers in the state of La Guaira.
Their mother remains missing, according to local television reports.
Television footage showed relatives and neighbours applauding as people were brought out from the rubble of collapsed buildings.
The disaster struck a country already grappling with years of economic turmoil that had left much of its infrastructure fragile, complicating rescue and recovery efforts.
In some areas, emergency workers scrambled over the debris of collapsed buildings through the evening and into Thursday.
In others, residents decried a lack of help.
Jorge Rodriguez, who heads Venezuela's national assembly and is the brother of interim President Delcy Rodriguez, said at least 188 people were confirmed dead and 200 were trapped.
He said 1520 people were injured and at least 250 buildings had been damaged or destroyed.
The worst-affected area, La Guaira state, near Caracas, "has become a disaster zone," President Rodriguez said, adding that her government was working with businesses to deploy heavy machinery to accelerate rescue efforts.
"He's under the slabs and there's no machinery to get him out," said La Guaira resident Yamileth Jimenez, whose 19-year-old son is believed trapped in the rubble of their seven-story apartment building.
"My father died three days ago and now this happens. It's just my son and me," Jimenez said.
Rescue workers were scarce in the state's coastal capital, also called La Guaira, where volunteers were digging with their bare hands.
"We lost everything. We have no food or medicines. We managed to get out in time and only have minor injuries … we hope help arrives quickly," said Pedro Perez, 64, the owner of an upholstery workshop.
He said he lost his home and business and had been forced out onto the streets with his wife and children.
Others in La Guaira searched for food and water.
Reuters witnessed looting at two stores there.
Caracas' main airport in La Guaira was closed on Thursday after suffering damage.
Witnesses' footage during the earthquakes showed scenes of panic as ceilings came down.
Many Venezuelans were at home when the quakes struck during a public holiday.
Residents fled shaking buildings and poured into the streets as structures collapsed across Caracas and nearby coastal areas.
Houses collapsed near the quake's epicenter in Morón, a small seaside town in the state of Carabobo, where there was no water or electricity.
Three children were among at least eight killed in the area, municipal Mayor Emily Riera told Reuters.
World leaders from across the political spectrum expressed solidarity with Venezuela, a notable shift from the international polarisation that has surrounded the country in recent years.
Rodriguez said international rescue teams were expected soon and thanked leaders including US President Donald Trump and Russian President Vladimir Putin.
with DPA
