Rescue workers scrambled to find survivors after a powerful 7.2-magnitude earthquake struck Haiti early Saturday, killing at least 304 and toppling buildings in the disaster-plagued Caribbean nation still recovering from a devastating 2010 quake.

The epicenter of the shaking, which rattled homes and sent terrified locals scrambling for safety starting around 8:30 am (1230 GMT), was about 100 miles (160 kilometers) by road west of the center of the densely populated capital Port-au-Prince.

Churches, businesses, schools and homes crumbled in the quake that trapped hundreds of victims under rubble and left at least 1,800 people injured, the country's civil protection agency said.

Rescuers raced against the clock to find survivors, with the civil protection tweeting that efforts by "both professional rescuers and members of the public have led to many people being pulled from the rubble," adding that already overburdened hospitals continue to receive injured.

Hours after the quake, the agency announced the death toll had jumped to 304, ticking upwards throughout the day from a first report of 29 fatalities.

The long, initial quake was felt in much of the Caribbean, emanating from the epicenter at Haiti's southwestern peninsula.

The civil protection said at least 160 people were killed in the country's South department alone.

"Lots of homes are destroyed, people are dead and some are at the hospital," 21-year-old Christella Saint Hilaire, who lives near the epicenter, told AFP.

Hospitals in the regions hardest hit by the quake were already struggling to provide emergency care and at least three in the municipalities of Pestel, Corailles and Roseaux were completely full, according to Jerry Chandler, head of the civil protection agency.

- State of emergency -

The health ministry quickly dispatched personnel and medicine to the southwestern peninsula, but arrival could be hampered by insecurity that has plagued the poorest country in the Americas for months.

The only road linking the capital to the southern half of the country passes through Martissant, an area that has been under the tight control of armed gangs since early June, blocking free passage.

"We all know that we have a problem in Martissant," said Prime Minister Ariel Henry during a press briefing on Saturday evening. 

"We decided... that all the aid must be able to pass through" to effected areas, he added, saying police and military forces had been deployed to that end, without providing further details. 

The United States and other nations swiftly pledged support to the crisis-wracked country, with US President Joe Biden approving "immediate" aid efforts.

"In what is already a challenging time for the people of Haiti, I am saddened by the devastating earthquake," Biden said, adding that his country was ready to "assess the damage and assist efforts to recover those who were injured and those who must now rebuild."

Images circulated on social media in the wake of the disaster showed people frantically trying to pull people from the ruins of caved-in buildings, while screaming bystanders sought safety in the streets outside their homes.

"Houses and their surrounding walls have collapsed. The roof of the cathedral has fallen down," resident Job Joseph told AFP from the hard-hit city of Jeremie on Haiti's far western end.

Heavy damage was reported in the center of the city, which is home to around 200,000 people and composed primarily of single-story residences and buildings.

The damage in the city of Les Cayes appeared to be significant, including the collapse of a multi-story hotel.

The prime minister, who surveyed the damage via helicopter, declared a state of emergency for one month while calling on the nation to "show solidarity" and not panic.

Shortly after the quake, the US Geological Survey (USGS) issued a tsunami alert, but lifted the warning soon after.

- 'People are terrified' -

Jeremie resident Tamas Jean Pierre said the possibility of a tsunami nonetheless sent parents "fleeing the city with their children in arms." 

"People are terrified," she said.

A 7.0-magnitude quake in January 2010 transformed much of Port-au-Prince and nearby cities into dusty ruins, killing more than 200,000 and injuring some 300,000 others.

More than a million and a half Haitians were made homeless, leaving island authorities and the international humanitarian community with a colossal challenge in a country lacking both a land registry and building codes.

The quake destroyed hundreds of thousands of homes, as well as administrative buildings and schools, not to mention 60 percent of Haiti's health care system.

The rebuilding of the country's main hospital remains incomplete, and nongovernmental organizations have struggled to make up for the state's many deficiencies. 

The latest quake comes just over a month after President Jovenel Moise was assassinated in his home by a team of gunmen, shaking a country already battling poverty, spiraling gang violence and Covid-19.