More than 700 people packed a church in Brampton, Ont. to say goodbye to a teen killed while trying to retrieve his lost cellphone.

Jeremy Ryan Cook, 18, was fatally shot after using an app to track the cellphone he'd left in a London, Ont., taxi cab last weekend.

"It is clear to us that Jeremy made a profound impact in his short time with us," family friend Maureen Di Iorio said through tears.

"His legacy will live on through the memories and relationships that he developed with so many wonderful family and friends."

Police said Cook and a relative tracked the phone to a parking lot at a mall in the city's north end. Cook approached three men in a silver 2004 Mazda, at approximately 5:20 a.m. on June 14. When the car began to drive away, police say Cook grabbed the driver's side door. Several shots were fired, and Cook succumbed to his injuries.

The Mazda drove away, before crashing into a pole and a fence. Cook's phone was later found near the abandoned vehicle.

Cook, who is originally from Brampton, was living in London while completing a carpentry internship. He planned to attend college in the fall, and was running his own furniture business on the side.

Approximately 750 people attended a 10 a.m. service at St. Anne's Roman Catholic Church, located at 115 Vodden St. E., in the Kennedy Road and Queen Street area of Brampton.

During the service, he was described as an ambitious young man with an "awesome" sense of humour and a passion for carpentry.

"Most of us might be asking similar questions like: Why? Why now, at this young age?" the pastor read during the sermon.

"Many of us may not understand the manner and heinousness of the way Jeremy died. It is unacceptable in a civilized society."

Acting as a spokesperson, Di Iorio told reporters at the funeral that the family wished to thank the teen's friends and the public.

"We've been strengthened by the tremendous outpouring of support and sympathy from so many people over the past week," Di Iorio said.

A classmate who attended the funeral said she couldn't believe what had happened to Cook.

"He was such a great kid, so kind."

Police searching for three men

On Friday, police said a Canada-wide arrest warrant had been issued for 23-year-old Muhab Sultanaly Sultan, of Calgary. Sultan, who remains at large, is wanted for second-degree murder.

They're also looking for a man described as having very short hair, and was wearing a black jacket or shirt and fitted hat. They said they are also hoping to speak with the third man seen in the vehicle, but they have yet to release a description.

Anyone with more information is asked to contact police at 519-661-5670, or Crime Stoppers anonymously at 1-800-222-8477 (TIPS).

With a report from CTV Toronto's Zuraidah Alman