A tropical depression that dumped heavy rains on parts of Puerto Rico and the Dominican Republic is expected to strengthen into a tropical storm on Sunday as it passes close to the Bahamas, the U.S. Hurricane Center said.

The depression formed over the Turks and Caicos Islands on Saturday. It is the fourth depression of the Atlantic hurricane season.

Late Saturday evening, the depression had sustained winds of 35 mph (55 kph) and was located about 90 miles (145 kilometers) northeast of Great Inagua island, the hurricane center said in a tropical advisory.

A tropical storm warning has been issued for the Turks and Caicos and for the southeast and central Bahamas, with forecasters saying it could bring up to 8 inches (20 centimeters) of rain. The depression was moving northwest near 9 mph (15 kph).

The storm was upgraded to a tropical depression on Saturday afternoon, and it had previously downed several trees and power lines in Puerto Rico, leaving more than 17,000 people without power and nearly 5,600 without water.

Police said in a statement that a small bridge collapsed Saturday in the central town of Barranquitas, isolating some 25 families in the area. No one was injured.