Haiti’s strongest earthquake in more than 200 years rocked the island nation on Tuesday, killing untold numbers of people and severely damaging several prominent buildings there, according to news reports.

The earthquake, which measured 7.0 on the Richter scale, collapsed a hospital where people screamed for help and heavily damaged the National Palace, U.N. peacekeeper headquarters and other buildings, according to The Associated Press.

Several eyewitnesses reported heavy damage and bodies in the streets of the capital, Port-au-Prince, where concrete-block homes line steep hillsides, according to CNN. There was no estimate of the dead and wounded Tuesday evening, but the U.S. State Department has been told to expect “serious loss of life,” department spokesman P.J. Crowley told reporters in Washington.

Haiti’s ambassador to the United States called the earthquake a catastrophe for the Western Hemisphere’s poorest nation.

“The only thing I can do now is pray and hope for the best,” the ambassador, Raymond Alcide Joseph, told CNN.

U.S. officials reported bodies in the streets and an aid official described “total disaster and chaos.”

United Nations officials said hours after the 7.0-magnitude quake struck at 4:53 p.m. that they still couldn’t account for a large number of U.N. personnel.

Communications were widely disrupted, making it impossible to get a full picture of damage as powerful aftershocks shook a desperately poor country where many buildings are flimsy. Electricity was out in some places.

Karel Zelenka, a Catholic Relief Services representative in Port-au-Prince, told U.S. colleagues before phone service failed that “there must be thousands of people dead,” according to a spokeswoman for the aid group, Sara Fajardo.