Hurricane Ida weakened to a Category 1 hurricane on Monday as it headed toward oil and gas facilities in the central Gulf of Mexico after killing 124 people in El Salvador following floods and mudslides.

Ida's top sustained winds fell to 90 miles per hour and was expected to weaken further in the next 24 hours, the US National Hurricane Center said. But Ida was still expected to be a hurricane as it approached the US Gulf Coast on Monday night or early on Tuesday, bringing heavy rains.

Ida was forecast to hit somewhere between Louisiana and Florida.

US oil companies were shutting production and evacuating workers from the Gulf in the face of Ida.

Oil rose more than $1 to above $78 a barrel on Monday on fears the hurricane would cut US oil and gas supplies.

A man carries a girl on a street damaged by heavy rains in Verapaz, about 71 km (44 miles) east to San Salvador November 8, 2009. [Agencies]

Several large producers shut down some oil and gas production as a precautionary measure.

The Louisiana Offshore Oil Port, the only terminal in the United States capable of handling the largest tankers, stopped unloading ships due to stormy seas.

A quarter of US oil and 15 percent of its natural gas are produced from fields in the Gulf and the coast is home to 40 percent of the nation's refining capacity.

In El Salvador, rivers burst their banks and hillsides collapsed under relentless rains triggered by Ida's passage, cutting off parts of the mountainous interior from the rest of the country.

El Salvador's government said 124 people were killed as mudslides and floods swept away rudimentary houses.

The bulk of the Central American country's coffee is grown in areas far from the worst affects of the flooding but the national coffee association had no estimate of potential damage to the harvest.

Louisiana state of emergency

The Miami-based hurricane center set a hurricane warning from Pascagoula, Mississippi, to Indian Pass, Florida, meaning hurricane conditions could be expected in the area within 24 hours.

A tropical storm warning was in effect for parts of Louisiana and Mississippi, including the city of New Orleans, which is still recovering from the devastation of Hurricane Katrina in 2005.

Louisiana Governor Bobby Jindal declared a state of emergency on Sunday, allowing the government to mobilize troops and rescue workers.

If Ida makes landfall in Louisiana, it would be the first storm to strike the state since Hurricane Gustav came ashore in September 2008.

At 4 am EST, the center of Ida was about 285 miles south-southeast of the mouth of the Mississippi River and 375 miles south of Pensacola, Florida. Ida was expected to turn toward the north and move faster toward the Gulf Coast before veering off to the northeast on Tuesday.

Ida swept past the Mexican resort of Cancun on Sunday, doing little damage to the city.

Ida first became a hurricane on Thursday off the Caribbean coast of Nicaragua, where heavy rains forced more than 5,000 people into shelters.

The country's coffee crop was not directly affected by the storm, according to the local coffee council.