Entrepreneurs turned to Twitter on Sunday to mourn the death of Colin Kroll, co-founder of the gaming app HQ Trivia and Vine, who was found dead of an apparent drug overdose. 

Police found the 34-year-old entrepreneur along with what appeared to be cocaine and heroine in his New York City apartment early Sunday, The New York Times reports. Kroll had taken over the CEO role at HQ Trivia in September, succeeding co-founder Rus Yusupov. He was previously the company's chief technology officer. Kroll also worked at Twitter as a general manager for roughly 18 months after the company acquired his six-second video app Vine in 2012. He was ultimately fired for "poor management," Recode reported last year. Twitter shuttered Vine in 2017. Kroll's official cause of death will be determined by the medical examiner's office. 

HQ Trivia held a memorial Sunday night. Here is what Yusupov and others had to say

Scott Rogowsky, one of the HQ Trivia's most popular hosts, expressed his gratitude.

Other entrepreneurs called attention to the startup ecosystem, including Backstage Capital's Arlan Hamilton and Alex Mather, founder of sports startup The Athletic.