Authorities evacuated 360 persons from a low-lying apartment development in Laurel as a "precautionary measure" last night as melting snow and continuing rain raised widespread concern throughout the Washington area about possible flooding.

The evacuations in Laurel were carried out between 8:30 p.m. and 10:30 p.m. at the 10 buildings of the Mistletoe Gardens apartments on Laurel Bowie road after flood waters from the nearby Patuxent River reached to the door of one of the buildings.

"Rather than evacuate people at two or three in the morning we figured we'd do it at a more reasonable hours, said Steve Hannestad, deputy director of the Prince George's County Department of Emergency Preparedness. Authorities said the evacuees were being sheltered last night at a Laurel elementary school.

The apartment complex is located on the banks of the river, which officials said had risen from a depth of two feet to more than nine since Saturday.

A number of smaller evacuations, also carried out chiefly as a precaution, were reported last night in Caroline County on Maryland's Eastern Shore and in low-lying areas along the Shenandoah River in Warren County, Va.

In a bulletin issued late last night, the National Weather Service predicted "moderate rises" along the Potomac, Patuxent, and Rappahannock rivers, but said forecasters expected "no major flooding."

The weather service said the Potomac is expected to rise to two feet above its flood stage at the foot of Wisconsin Avenue at 7 a.m. today. Flood stage there is listed as seven feet.

Forecasters said water probably would cover low-lying areas immediately adjacent to the river, including parking areas between K Street and the river.

Yesterday's rain, which averaged about an inch and a quarter over the Potomac basin, flooded numerous roads and basements, swamped several bridges, apparently caused the collapse of two basements in Montgomery County and prompted a flash flood watch through today.

Two Patuxent River crossings -- the Brock Bridge and another bridge that carries Rte. 198 between Prince George's and Anne Arundel counties -- were closed yesterday after they were submerged in water from the swollen river.Prince George's County authorities reported about a dozen secondary roads closed because of flooding.

In Fairfax County, several thoroughfares were reported shut, including the intersection of Huntington and Telegraph roads near the Capital Beltway in the Mount Vernon area.

In the District of Columbia, no major street flooding was reported yesterday.At least two thoroughfares -- a section of New York Avenue NE between Bladensburg Road and South Dakota Avenue and the northbound lanes of I-295 near Pennsylvania Avenue in Southeast Washington -- were closed because of severe potholes, according to D.C police.

Last night, D.C. officials announced an emergency all-night effort to temporarily repair potholes in major commuter routes in order to make them passable for today's rush hours. Permanent patching will begin when the rain lets up, probably on Tuesday, officials said.

In Laurel yesterday, Prince George's County police, fire and other emergency officials set up a command post to monitor the rising Patuxent River and the water level behind the 100-foot-high Duckett Reservoir Dam a mile north of the city.

Well before last night's evacuation of the Mistletoe Gardens, officials had urged Laurel businesses and residents to move their vehicles to high ground, and warned persons living in areas near the river to be prepared to evacuate.

As of late last night, more than 2 1/2 inches of rain had been measured at National Airport since Friday. Forecasters said the heavy rains have been spawned by a storm that originated in the Mississippi Delta and was centered over southwestern Virginia last night. The storm was due to pass over Washington this morning and then move northeastward up the coast, they said.

Officials in Arlandria, a low-lying section of Alexandria and Arlington County historically prone to severe flooding, said last night that there seemed no imminent danger from Four Mile Run. As part of a flood control project started in 1974, Four Mile Run currently is being widened and channeled by construction crews to improve drainage.

Alexandria police said sirens would alert Arlandria residents if Four Mile Run rises to its banks.