A powerful earthquake rocked the eastern Caribbean on Thursday, sending office workers and shoppers fleeing into the streets of several islands. There were no immediate reports of casualties. The earthquake, with a magnitude of 7.4, was centered 42 kilometers southeast of Roseau, the capital of Dominica, where the shaking lasted for about 20 seconds. The quake was felt hundreds of kilometers away in Puerto Rico to the west, and Venezuela and Suriname to the south. Radio hosts at Radio Martinique said the earthquake caused some damage on the French island and urged people to evacuate buildings. "My house shook so hard I thought it was going to fall," said a caller who identified herself only as Fannie. "The door, the windows, everything shook."