ROUND ROCK, Texas (AP) — The suspect in a series of bombing attacks in Austin blew himself up early Wednesday as authorities closed in, a dramatic end to a weekslong siege of the Texas capital, where two were killed and four injured in a series of blasts.

Authorities had zeroed in on the suspect in the last 24 to 36 hours and located his vehicle at a hotel on Interstate 35 in the Austin suburb of Round Rock, Austin Police Chief Brian Manley said at a news conference. They were waiting for ballistic vehicles to arrive to move in for an arrest when his vehicle began to drive away, Manley said. Authorities followed the vehicle, which ran into a ditch on the side of the road, the police chief said.

When members of the SWAT team approached, the suspect detonated an explosive device inside the vehicle, the police chief said. The blast knocked back one officer, while a second officer fired his weapon, Manley said.

Authorities identified the suspect only as a 24-year-old white man and wouldn’t say if he was from Austin.

Austin has been targeted by four package bombings since March 2 that killed two people and wounded four others. A fifth parcel bomb detonated at a FedEx distribution center near San Antonio early Tuesday.

The Austin, Texas Police Department says it is working an “Officer Involved Shooting” on Wednesday morning. There is heavy police activity on I-35 in Round Rock. It is unclear if this connected to the bombings in Austin. (March 21)

Manley said the suspect is believed to be responsible for all the major Austin bombings, but authorities acknowledged it was too soon to say if the suspect had worked alone. Authorities also said they didn’t know his motive.

FBI agent Chris Combs, head of the agency’s San Antonio office, said, “We are concerned that there may be other packages that are still out there.”

Isaac Figueroa, 26, said he and his brother heard sirens and helicopters early Wednesday and drove toward them, then cut through nearby woods on foot after they hit a police roadblock.

Figueroa said they saw a silver or gray Jeep Cherokee that was pinned between black and white vehicles and “looked like it had been rammed off the road.” He said he saw police deploy a robot to go examine the Jeep.

President Donald Trump, who had earlier said whoever was responsible for the Austin bombings was “obviously a very sick individual or individuals,” tweeted, “AUSTIN BOMBING SUSPECT IS DEAD. Great job by law enforcement and all concerned!”

The suspect’s death followed a day of rapid-fire developments in the case.

On Tuesday, a bomb inside a package exploded around 1 a.m. as it passed along a conveyer belt at a FedEx shipping center in Schertz, northeast of San Antonio and about 60 miles (95 kilometers) southwest of Austin. One worker reported ringing in her ears and was treated at the scene.

Later in the morning, police sent a bomb squad to a FedEx facility outside the Austin airport to check on a suspicious package. Federal agencies and police later said that package had indeed contained an explosive that was successfully intercepted and that it, too, was tied to the other bombings.

Authorities also closed off an Austin-area FedEx store where they believe the bomb that exploded in Schertz was shipped. They roped off a large area around the shopping center in the enclave of Sunset Valley and were collecting evidence.

The Schertz blast came two days after a bombing wounded two men Sunday night in a quiet Austin neighborhood about 3 miles (5 kilometers) from the FedEx store. It was triggered by a nearly invisible tripwire, suggesting a “higher level of sophistication” than agents saw in three package bombs previously left on doorsteps, according to Fred Milanowski, the agent in charge of the Houston division of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives.

Authorities have not identified the two men who were hurt Sunday, saying only that they are in their 20s. But William Grote told The Associated Press that his grandson was one of them and that he had what appeared to be nails embedded in his knees.

During an Oval Office meeting Tuesday, President Donald Trump said whoever is responsible for the bombings “is obviously a very sick individual or individuals” and that authorities are “working to get to the bottom of it.”