Two transgender women of color were killed over the weekend in Dallas and Philadelphia, and an arrest has been made in one of the murders.

Muhlaysia Booker and Michelle Washington were killed less than 24 hours apart in separate incidents. They are among at least five transgender people — all of whom were black — who have been killed nationwide in 2019, according to advocacy group the Human Rights Campaign.

Washington, 40, who was also known by the names Tamika and Michelle Simone, was shot multiple times in Philadelphia on Sunday morning.

An arrest was made in Washington's murder, police announced Tuesday.

Troy Bailey, 28, was arrested Monday night and charged with murder and other firearms-related charges, police said.

Bailey went to police on Monday and told investigators he was an eyewitness to the shooting, Philadelphia homicide Capt. Jason Smith told reporters Tuesday at a news conference. Bailey later admitted to police that he shot Washington in the head and torso following a dispute over the sale of a firearm, Smith said.

"The truth as to why Mr. Bailey murdered Ms. Washington may never be fully known," Smith said. "According to Mr. Bailey, it was over a dispute that the two had pertaining to the sale of a firearm from Mr. Bailey to Ms. Washington."

Smith said police do not "necessarily believe that's the case."

They are not investigating Washington’s murder as a hate crime.

On Saturday morning, Booker, 23, who survived a brutal April 12 beating in Dallas that was captured on cellphone video and went viral, was found lying face down on a street northeast of downtown Dallas.

Muhlaysia Booker via Facebook

The Dallas Police Department said officers had been responding to a report of a shooting and found Booker "deceased from homicidal violence," but did not provide more details. There have been no arrests in Booker's death and police are investigating if it should be treated as a hate incident, Dallas Police Maj. Vincent Weddington said at a Tuesday news conference.

Edward Thomas, 29, was charged with assault in the beating that was caught on video. He is not being held in jail, and police said over the weekend there is no evidence connecting him to Booker's killing.

The deaths of Booker and Washington were mourned by advocacy groups.

“The news of the murder and death of Michelle ‘Tamika’ Washington has hit so many in our community hard," said Raquel Evita Saraswati, chair of Philadelphia Mayor Jim Kenney’s Commission on LGBT Affairs. "More than a news story, she was a friend, a loved one, a beloved."

Troy Bailey Philadelphia Police Department

Charlotte Clymer, Human Rights Campaign press secretary, said Booker was a "courageous voice against the violence she experienced" in April.

"This epidemic of violence that disproportionately targets transgender people of color — particularly black transgender women — must cease," Clymer told NBC News Tuesday.

At least 26 transgender people died in 2018 because of fatal violence, according to Human Rights Campaign. The majority of victims were people of color.

A 2018 report released by Human Rights Campaign on anti-transgender violence in America, titled "A National Epidemic," found that most victims are young, female-identified and black.