Hurricane Sally came ashore near the Florida-Alabama line Wednesday with 105-mile-per-hour winds and rain measured in feet, swamping homes and trapping people in high water.

Moving slowly, the storm made landfall at 4:45 a.m. near Gulf Shores, Alabama, battering nearby Mobile, Alabama, and Pensacola, Florida, areas with a population of almost 1 million.

Emergency crews rescued people from flooded homes. Thousands more are expected to flee rising waters in the coming days. Escambia County officials urged residents to stick to text messages for contacting family and friends to keep cellphone service open for 911 calls.

“There are entire communities that we’re going to have to evacuate,” County Sheriff David Morgan said. “It’s going to be a tremendous operation over the next several days.”

More than two feet of rain was recorded near Naval Air Station Pensacola, and nearly three feet of water covered streets in downtown Pensacola, the National Weather Service reported. The storm knocked out power to about a half-million homes and businesses.

“It’s not common that you start measuring rainfall in feet,” said forecaster David Eversole in Mobile. “Sally’s moving so slowly, so it just keeps pounding and pounding and pounding the area with tropical rain and just powerful winds. It’s just a nightmare.”

Streetlights were knocked out in downtown Mobile, a city of about 190,000. Trees were bent over as the rain blew sideways in the howling wind. In downtown Pensacola, car alarms went off, the vehicles’ flashing lights illuminating the surrounding floodwaters.

Michele Lamar-Acuff woke to the thud of a small tree falling against a window of her Pensacola home. Waist-deep water gushed down her street. Above the loud whistling of the wind she heard what sounded like transformers exploding.

“I don’t feel safe to leave,” Lamar-Acuff said from the porch of a neighbor’s house. “I’m just staying put and hoping for the best.”

Sally blew ashore as a Category 2 storm but weakened to a still-dangerous Category 1, with winds of 80 miles per hour, by midmorning. Forecasters warned that heavy rain will continue Thursday as the storm moves through Alabama into central Georgia.