PORT-AU-PRINCE (Reuters) - A major earthquake hit the impoverished country of Haiti on Tuesday, collapsing buildings in the capital Port-au-Prince and burying residents under rubble, a Reuters reporter in the city said.

He said he saw dozens of dead and injured people in the rubble, which blocked streets in the city. The epicenter of the quake was located inland, only 10 miles from the capital Port-au-Prince and was very shallow at a depth of only 6.2 miles.

It prompted a tsunami watch for parts the Caribbean, the Pacific Tsunami Warning Center said on Tuesday.

"Everything started shaking, people were screaming, houses started collapsing ...

... it's total chaos," Reuters reporter Joseph Guyler Delva said. "I saw people under the rubble, and people killed," he added. A local employee for the U.S. charity Food for the Poor reported seeing a five-storey building collapse in Port-au-Prince, a spokeswoman for the group, Kathy Skipper, told Reuters.

Another Food for the Poor employee said there were more houses destroyed than standing in Delmas Road, a major thoroughfare in the city.

Panic-stricken residents filled the streets desperately trying to dig people from rubble or seeking missing relatives as dark fell shortly after the quake.

"People were screaming 'Jesus, Jesus' and running in all directions," Delva said.

A major earthquake, of magnitude 7 or higher, is capable of causing widespread and heavy damage. There was no immediate report of damage or casualties.

The tsunami center said the watch was in effect for Haiti, the neighboring Dominican Republic, with which it shares the island of Hispaniola, Cuba and the Bahamas.

"A destructive widespread tsunami threat does not exist based on historical earthquake and tsunami data," the center said. "However, there is the possibility of a local tsunami that could affect coasts located usually no more than a 100 km (60 miles) from the earthquake epicenter."

The quake was quickly followed by two nearby, strong aftershocks of initial magnitude of 5.9 and 5.5,

(Writing by Sandra Maler and Pascal Fletcher; Editing by David Storey)

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