Five people were killed in West Texas in a wreck Monday on a highway being used as a detour for a washed-out bridge, and South Texas was on watch for possible flooding from the slow-moving storm system that dumped up to four inches of rain the day before.

Meanwhile, the number of people killed in a flash flood in the Mexican border city of Piedras Negras rose to at least 25, with dozens of people reported missing.

The National Weather Service (search) had flood warnings in effect into Tuesday in a triangle roughly formed by San Antonio, Corpus Christi and Laredo.

The deaths in West Texas occurred in a four-vehicle wreck on a two-lane road in Reeves County, according to the state Department of Public Safety. The road was being used as a detour for eastbound traffic on I-20, after a bridge over the Salt Draw, a ravine, was washed away Sunday evening.

Two semitrailers and a pickup truck were involved, DPS spokesman Tom Vinger said.

Three of those killed were believed to be undocumented workers from Mexico traveling in a lettuce truck that crashed head-on with a semi, Vinger said. The lettuce truck's driver was also killed. The fifth person killed was driving the pickup, which smashed into the overturned lettuce truck.

No one was hurt when the bridge crumbled into the normally dry Salt Draw about 15 miles west of Pecos. Authorities said they had warning and were able to close the highway.

"The water below the bridge looks like the Mississippi — strong, muddy-brown currents," he said.

Throughout West and South Texas, residents battled high waters and hail storms. A portion of a grocery store roof collapsed in Crystal City, about 80 miles southwest of San Antonio, after eight inches to a foot of hail blanketed the region Sunday.

In New Mexico, water released from an overloaded dam added to floodwaters in the Carlsbad area Monday, as the swelling Pecos River flooded underpasses and forced school closures. Carlsbad and Eddy County declared a joint state of emergency after three days of storms drenched the area with more than 4 inches of rain.

During the weekend, dozens of people were evacuated, including some who were airlifted out by military helicopter. Eighteen spent Sunday night in a hotel, although they were free to return home any time, Carlsbad emergency spokeswoman Liz Baggs said.

"The water knocked out the underpinnings from our house," said Leroy Power.

Claude and Mary Arnold said roaring floodwaters edged within inches of their front door and debris swept along by the current knocked against their house.

"The noise from the rushing water was awful," Mary Arnold said.

In Piedras Negras, across the Rio Grande (search) from Eagle Pass, at least 25 people were killed when the Escondido River (search) swelled early Monday and swept through a working-class neighborhood of tin-roofed shacks.

At least 60 more people were reported missing, according to a local Red Cross official in the city of 200,000, and hundreds were forced into shelters.