The family and friends of two young men killed in separate slayings on the streets of Philadelphia this week gathered Thursday to remember them at sorrowful vigils.

For Samir Jefferson, 14, who was gunned down Monday afternoon while waiting for a SEPTA bus in Feltonville, about 200 people clutching black, red, and silver balloons gathered outside Mastery Charter School Harriett Elementary in West Philadelphia.

For Samuel Collington, 21, a senior at Temple University who was killed in a botched carjacking Sunday after returning from spending the Thankgiving holiday with his family, loved ones clutched candles outside Interboro High School in Prospect Park, Delaware County.

At the vigil for Jefferson, his mother arrived in tears, was embraced by supporters, and left without speaking. A tight circle of those who gathered then released the balloons into the early evening sky.

Diana Jefferson, the teen’s great-grandmother, described him as a “funny-acting, silly, good kid” who loved basketball and used to attend the school in front of which the crowd gathered.

“Love your children,” she told the crowd. “Love is the key word. Hug them and tell them that you love them because you never know the day that you might be standing here.”

Police have made arrests in both crimes. On Wednesday two men were charged with murder, conspiracy, and other offenses in the death of Jefferson and police were seeking three more suspects on arrest warrants. Police have not released a motive for the killing.

Quadir Johnson, 21, of Logan, and Kyair Garnett, 21, of Strawberry Mansion, were charged in the slaying of the teen outside a Rite Aid pharmacy on the northeast corner of West Wyoming and Rising Sun Avenues.

Police said the two pulled up in one or two vehicles, got out and began firing. The teen ran about 200 feet east on Wyoming before collapsing on the sidewalk. The men chased him and continued shooting, striking him at least 10 times and leaving a trail of at least 35 shell casings from two handguns.

In the slaying of Collington, who had been expected to graduate in May and go on to law school, police charged Latif Williams, 17, of Olney, with murder and related crimes. Police said Collington was killed after he parked his mother’s SUV on the 2200 block of North Park Avenue near the school’s North Philadelphia campus. His death brought calls for increased safety measures at Temple.

Both killings added to the city’s growing toll of homicides. As of Thursday morning, 512 slayings had been recorded in the city, a 12% increase from the 457 slayings recorded at this time last year, according to the Philadelphia Police Department. The previous record in a year was 500 in 1990.