According to police, the rising senior was driving north on Greenspring Avenue about 10:20 p.m., approaching Highview Drive, when he lost control of his car and it left the roadway and struck a tree. He was flown to Maryland Shock Trauma, where he died, police said.
But his coaches spoke warmly of a teenager who cracked jokes but swam intensely, who was competitive but a vocal supporter of his teammates.
"The entire team is devastated," said Scott Ward, head coach for McDonogh, which won the Maryland Interscholastic Athletic Association A Conference championship meet in February.
"You just don't have too many kids like Alec come through the door," said Erik Posegay, a high-performance coach at the NBAC who last saw Cosgarea at the club's last swim meet of the summer Monday night, just hours before Alec's death.
"He was definitely a rising star in this sport."
After the meet, Posegay said, Alec went to dinner with other swimmers, per tradition, then headed back to his family's home on Alterwood Lane in Owings Mills.
Sometime after, his 2006 Ford Fusion left the roadway, police said. Evidence at the scene of the accident showed Cosgarea was driving above the speed limit, police said.
Ward, who coached Cosgarea at McDonogh for two years in middle school and three years on the varsity team, called the teen "a truly outstanding young man and exactly who you would want on your team."
Ward said Cosgarea was rarely without a smile on his face, but never far from focus.
"He could be [joking], and then kind of flip that switch when he needed to be a competitor," Ward said. "He was very good under pressure."
Cosgarea was a school record holder and an All-American, and won the 100-yard butterfly in this year's MIAA championship meet, Ward said. But he also didn't complain when coaches yanked him from a backstroke race at the same meet.
"He was all about whatever it would take for the team to win," Ward said.
Posegay said Cosgarea loved the sport and came to each practice with new goals.
In a statement, Bob Bowman, head coach and CEO of the NBAC, who is in Knoxville, Tenn., working with the Olympic team and coaching the club's most famous alumnus,Michael Phelps, said the whole club is grieving Cosgarea's death.
"Alec began swimming for NBAC at age six and demonstrated determination and versatility in his career," Bowman wrote. "Alec is an example to our athletes in how he trained, how he competed and the standards that he held himself to, which will continue to inspire and motivate his teammates and coaches."
Viewings will be held Friday at the Ruck Funeral Home, 1050 York Road in Towson, from 2 p.m. to 4 p.m. and 7 p.m. to 9 p.m.
A funeral mass will be held Saturday at the Cathedral of Mary Our Queen, 5200 N.Charles St.in Baltimore, at 10 a.m.