One child, 5-year-old Saa'yon Griffin, survived.
Akhmedov and Holloman stopped at the scene, said Sgt. Joseph Rossa of the Police Department's Accident Investigation Division. Each was held Thursday on $2.5 million bail.
Rossa said the drivers were traveling well above the speed limit, which varies from 40 to 45 m.p.h. in that area. The drag race could have been a random encounter, Rossa said, but police are looking into whether the men have a previous connection.
Akhmedov emigrated from Uzbekistan in 2003 and became a U.S. citizen in 2010.
Court records reveal a pattern of dangerous driving in several counties, including convictions for speeding, driving recklessly, and driving without a valid license.
In June 2009, Akhmedov was found guilty of speeding and driving without a license in York County.
Later that year in East Lampeter Township, Lancaster County, Akhmedov pleaded guilty to operating without a valid inspection. Two weeks later, he was convicted after Lancaster City police cited him for driving with a suspended or revoked license. Those charges were upheld in an appeal to Lancaster County Court.
In Lancaster in January 2010, Akhmedov pleaded guilty to disobeying a traffic-control device.
His tally of speeding violations grew when over the span of a year, he was twice convicted for speeding and also was cited in a third case that is pending.
Lower Southampton police in Bucks County cited Akhmedov for driving 17 m.p.h. over the limit in May 2012. A few months later, state police cited him for speeding in Cumberland County. And in May, he was charged with speeding on the Pennsylvania Turnpike near King of Prussia. That case remains open.
His license was reinstated in 2012 after being suspended in 2011, Rossa said. Why it was reinstated after speeding convictions in 2012 and a charge in 2013 was unclear.
Akhmedov has had other legal troubles. In April, he was arrested by federal authorities on charges he conspired with six others to defraud Medicare.
He worked as an emergency medical technician for Penn Choice Ambulance Inc. He and six others associated with the company allegedly provided patients with unnecessary rides and billed Medicare for the service. An indictment alleges that the group submitted more than $3.6 million in fraudulent claims to Medicare from September 2009 through January 2013.
He was released from custody on $100,000 unsecured bail after his April 10 arrest and has pleaded not guilty, according to court papers and Martin Isenberg, his lawyer.
Isenberg said he had talked with Akhmedov since the fatal Boulevard accident. He said his client was "very upset about what occurred" as well as "remorseful and scared."
Akhmedov is a married father with a young child, Isenberg said.
Police have confiscated both vehicles for evidence. Investigators will have to shut down the Boulevard to do forensic testing. Toxicology-test results on the drivers have not come back yet.
While speeding on the Boulevard is an issue, Rossa said, drag racing is not as common in the city as it used to be. He said drag racing as a cause of death has happened only one other time in the last four years, where a racer lost control of his car, crashed, and died. That incident was not on the Boulevard.
Contact Sulaiman Abdur-Rahman at sabdur-rahman@
phillynews.com or follow on Twitter @sabdurr.
Inquirer staff writer Robert Moran contributed to this article.