Hurricane Ike barreled across the warm, energizing waters of the Gulf of Mexico Wednesday on its way toward the Texas coast after crashing through Cuba's tobacco country and toppling aging Havana buildings.

The storm grew from a Category 1 to a Category 2 storm Wednesday as it strengthened over open waters after leaving Cuba and could grow into a massive Category 3 storm before slamming into Texas or northern Mexico on Saturday.

Ike has already killed at least 80 people in the Caribbean, and Texas put 7,500 National Guard members on standby and urged coastal residents to stock up on supplies.

The U.S. Federal Emergency Management agency still was uncertain about the timing of evacuations along the coast.

Click for tracking maps and satellite images at MyFOXHurricane.com.

Click for more from the National Hurricane Center.

Click to view Cuba Doppler radar imagery.

Cuban state television said some 2.6 million people — nearly a fourth of the island's population — sought refuge from Ike, which killed four people and shredded hundreds of homes as it swept across the country. Power was still spotty in Havana on Wednesday morning.

As it left Cuba, Hurricane Ike delivered a punishing blow to towns such as Los Palacios, which already suffered a direct hit from a Category-4 Hurricane Gustav on Aug. 30.

In a poor neighborhood along the train tracks, the combined fury of Ike and Gustav left nearly two-thirds of the wooden homes leveled or without roofs.

"The first one left me something, but this one left me nothing," said Olga Atiaga, a 53-year-old housewife. Gustav obliterated her roof and some walls. Then Ike blew away a mattress and smashed the kitchen sink.

"I don't even have anything to sleep on," she said.

Odalis Cruz, a 45-year-old housing inspector, said she evacuated to a shelter in the town's rice mill when it became clear Ike was following Gustav's path through Pinar del Rio, the westernmost province where Cuba produces tobacco used in its famous cigars.

She surveyed the damage to her home Tuesday.

"We repaired the roof two days ago and this one took the new one," she said. "I'm ready to move to Canada! We have spent eight days drying out things, cleaning everything, sleeping on the floor, and now we are hit again."

Gustav damaged at least 100,000 homes but didn't kill anyone because of massive evacuations. Cubans were ordered to evacuate for Ike as well, with those in low-lying or wooden homes seeking safety with friends or relatives in sturdier structures. Others were taken to government shelters.

State television said two men were killed removing an antenna from a roof, a woman died when her home collapsed and a man was killed by a falling tree.

Evacuations are not mandatory except for pregnant women and small children, but in an authoritarian state, few people ignore the government's advice.

In Havana, towering waves broke over the seaside Malecon promenade as downpours soaked historic but crumbling buildings in the capital's picturesque older areas. Some of the most dilapidated structures collapsed, including four houses on a single block.

Police told 21-year-old Niyel Rodriguez she had to move to a shelter with her 19-day-old daughter Chanel. She huddled Tuesday with 109 expectant and new mothers and their children in a wing of an Old Havana maternity hospital.

"They came looking for me yesterday and brought me here in a patrol car," Rodriguez said. "I probably would have been scared to stay at home with my little one, and here they take good care of us."

Elsewhere in Cuba, officials evacuated about 10,000 tourists from vulnerable seaside hotels, mostly from Varadero beach, east of Havana.

While Ike was expected to strengthen before making landfall again, oil prices closed below $104 a barrel for the first time since early April, in part because traders were betting Ike would miss critical Gulf Coast oil installations.

Mexican officials warned that unrelated heavy rains in the northern part of the country had caused more than a dozen dams to reach capacity or spill over. If Ike brings more rain to the area, evacuations may be needed.

Ike was centered about 145 miles north of the western tip of Cuba Wednesday morning and about 430 miles southeast of the mouth of the Mississippi River.

It was moving northwest at 8 mph. Maximum sustained winds remained near 85 mph, still at Category 1 storm.

Meanwhile, Tropical Storm Lowell has weakened to a tropical depression off Mexico's Pacific coast and it was expected to move across the Baja California Peninsula Wednesday night or Thursday morning. It had maximum sustained of near 35 mph.