On the Border, Police Chase Smugglers. The Migrant Body Count Is Getting Higher.

HOUSTON — A vehicle packed with undocumented migrants crashed in rural South Texas after it was chased by police, veering into a ditch in rainy weather and killing six people who were found Wednesday morning — the latest in a series of deadly crashes involving immigrants near the border.

The crash occurred on the outskirts of the town of Robstown, about 20 miles west of Corpus Christi.

The S.U.V. was packed with more than a dozen migrants and had been speeding when a Robstown police officer tried to pull it over on Tuesday evening, the authorities said. The driver sped away in the rain, and the police ended the chase when the officer lost the vehicle in a brush-covered area.

At some point after the chase, the driver of the S.U.V. appeared to have lost control and crashed into a drainage ditch next to a dirt road in a field. Authorities discovered the wreckage at the bottom of the 15-foot-deep ditch hours later.

Six men were found dead inside the vehicle. Six other men were outside the vehicle, and another man was found later nearby. All seven of the injured migrants were transported to local hospitals, and the authorities on Wednesday were still searching for the driver, who appeared to have escaped, officials said.

"In my 13 years, it's one of those that's up there — it was a gruesome scene," Roland Padilla, the Robstown emergency medical services chief, told reporters on Wednesday.

All of the migrants in the S.U.V. were from either Guatemala, Honduras, El Salvador or Mexico. They were all men in their late teens and early 20s, officials said.

The death toll from vehicle chases or single-car accidents involving smuggled migrants has steadily risen in recent years. In South Texas alone, more than 40 undocumented men, women and children have been killed since 2012.

Smugglers routinely transport migrants on the roads and highways in Texas border cities, often picking them up from stash houses, dropping them off near Border Patrol checkpoints, guiding them on foot through the brush and then later picking them up again just north of the checkpoints. The migrants themselves are rarely behind the wheel.

The drivers are usually smugglers who are paid to escort the migrants. Many of these drivers refuse to pull over if the authorities become suspicious of the vehicles, and they lead the Border Patrol, police officers and sheriff's deputies on dangerous, high-speed chases, often in rural areas.

"This is not an uncommon event," J.C. Hooper, the sheriff of Nueces County, which includes Robstown, told reporters Wednesday.

In April 2012, Border Patrol agents attempted to pull over a minivan near McAllen, Tex. The teenage driver stopped on the side of the road but then sped away, crashed and rolled over. Nine of the 16 migrants inside the minivan were killed.

Months later, in July 2012, a Ford pickup crammed with more than 20 undocumented adults and children veered off a highway near the South Texas town of Goliad and struck two trees, killing 15 migrants. The youngest fatality was a girl about 8 years old.

In 2015, six people were killed near Edna, Tex., after the driver of an S.U.V. filled with migrants fled from officers and lost control. The vehicle, which flipped over repeatedly and ejected several passengers, had been carrying undocumented adults from Honduras, Guatemala and Mexico.

And last June, five migrants in an S.U.V. were killed after the vehicle crashed on a highway outside the town of Big Wells, Tex., while being pursued by sheriff's deputies and Border Patrol agents.

Law enforcement agencies on the border have been criticized for being too aggressive during vehicle chases. In 2012, a Texas Department of Public Safety helicopter joined the pursuit of a speeding truck near the border, and an officer inside the helicopter opened fire with a high-powered rifle in an attempt to shoot one of the truck's tires. The officer ended up shooting and killing two Guatemalan migrants hiding in the bed of the truck.

The sheriff of Brooks County, a rural South Texas county that is home to a busy Border Patrol checkpoint north of McAllen, said there were three to four smuggling-related vehicle chases a week in his county.

"It's pretty constant," Sheriff Benny Martinez said. He defended his deputies' handling of the pursuits and the overall law enforcement response to the problem on the border.

"This is not really a regular stop at all, not when you have the criminal element behind that wheel," Sheriff Martinez said. "Their main objective is to either hit a fence-line or find a way to get out so they themselves can escape, the driver. It's dangerous for everyone, especially when they're busting through intersections. It's one of those Catch-22s. If we don't do it, shame on us. If we do it, shame on us."

On Wednesday, Robstown police officials said the S.U.V. crash was not a direct result of the police pursuit.

Sheriff Hooper said that at about 4 a.m. Wednesday, a resident reported that a man who appeared to have been injured had knocked at the resident's door. The man was never found, but shortly after, the authorities were called again to the area when two juvenile men who appeared to be wounded were spotted nearby. Those two men were apprehended.

It wasn't until shortly after 7 a.m. that the crash scene was finally located, the sheriff said.