Suspect allegedly chased Delaware state trooper before gunning him down, police say

— -- The 26-year-old suspect who allegedly shot and killed a Delaware state trooper on Wednesday chased the officer before gunning him down, police said.

The suspect, identified today as Burgon Sealy, allegedly shot 32-year-old Cpl. Stephen Ballard, and then fled to his home, where he held a 20-hour standoff with police. He was later shot and killed by police after he emerged carrying a weapon, ABC affiliate WPVI reported.

Here is a timeline of how the standoff unfolded:

Wednesday

Around 10 a.m.

Ballard observed what police described as a suspicious vehicle in the parking lot of a Wawa convenience store in Bear, Delaware on the Pulaski Highway. In a press conference Thursday, state police said that they think Ballard "had a reason to stop" the red Dodge Charger and that it could have been "drug involvement."

The trooper, dressed in full uniform, made contact with both the driver and the passenger, who showed their IDs, police said. When Ballard walked to the passenger side of the car, he asked Sealy to step out of the vehicle, and a struggle ensued.

Sealy allegedly removed a firearm from his waistband and pursued Ballard in the parking lot. Ballard tried to take cover behind a parked vehicle, but when he fell, Sealy allegedly fired several rounds at him, striking him.

The driver of the car stayed on the scene until more troopers arrived and was taken into custody without incident. He was later released.

Ballard was treated on the scene and transported to a local hospital.

Around 3 p.m.

All schools in the Appoquinimink School District in the Middletown, Delaware area are placed on lockdown amid the search for Sealy.

Around 4:45 p.m.

State police announce at a press conference that Ballard has succumbed to his injuries and that Sealy had barricaded himself in his home on St. Michaels Drive in the Brick Mill Farm development.

After he fled, Sealy had contacted family members to inform them that he had shot the trooper, police said. The family members then contacted law enforcement, who traced Sealy to his home.

Sealy fired several rounds at police officers. Residents in the area were evacuated due to the gunfire.

Hostage negotiators on the scene attempted to get information from the suspect and to obtain a "peaceful resolution," police said.

7:32 p.m.

Delaware Gov. John Carney announced that U.S. and state flags will be flown at half-staff in Ballard's honor.

8:22 p.m.

Sealy stopped making contact with police on the scene, who set up an explosive charge on the residence. Authorities did not enter the home but continued attempts to make contact with Sealy to persuade him to surrender.

9:35 p.m.

Police identify Ballard as the trooper who was killed. He was an eight-year veteran of the Delaware State Police, police said.

Thursday

4 a.m.

Sealy allegedly began firing at officers again, and authorities continued to try to negotiate with him. The Odessa Fire Company had opened its facility to temporarily house the residents in the area who had been evacuated.

9:17 a.m.

Sealy exited the home with a weapon, according to officials. He was then shot by law enforcement.

9:29 a.m.

Sealy is pronounced dead on the scene. About 25 minutes later, police confirm to ABC News that the standoff is over.

ABC News' Courtney Connley, Matt Foster, William Gretsky and Rachel Katz contributed to this report.