This booking photo provided by the Tampa Police Department, Fla., on Wednesday, Nov. 29, 2017, shows Howell Emanuel Donaldson. Donaldson, the suspect in a string of four slayings that terrorized a Tampa neighborhood was arrested after he brought a loaded gun to his job at a McDonald's and asked a co-worker to hold it, authorities said. (Tampa Police Department via AP)
This booking photo provided by the Tampa Police Department, Fla., on Wednesday, Nov. 29, 2017, shows Howell Emanuel Donaldson. Donaldson, the suspect in a string of four slayings that terrorized a Tampa neighborhood was arrested after he brought a loaded gun to his job at a McDonald's and asked a co-worker to hold it, authorities said. (Tampa Police Department via AP)

A recent college graduate who was charged in four slayings that terrorized a Tampa neighborhood over the past 51 days used the same gun in all of the shootings and targeted people near bus stops with “no apparent motive,” a police chief said Wednesday.

The crack in the case came Tuesday when Howell Emanuel Donaldson, 24, brought a bag with a loaded handgun in it to his job at a McDonald’s and asked a co-worker to hold it while he went across the street, authorities said.

Restaurant workers thought that was odd and when Donaldson left, they reported the gun to a police officer, setting off an investigation that linked Donaldson to the shootings. Aside from matching shell casings at the shootings, authorities said location data from Donaldson’s cellphone put him at the scene of at least three of the killings.

The arrest overnight brought relief to an anxious community worried about a serial killer. The first shooting happened Oct. 9, followed by two more shooting deaths. By Halloween, the fear was so great that police escorted children while trick-or-treating. The fourth killing happened earlier this month.