Colin Kroll, the CEO and co-founder of HQ Trivia was found dead in his New York City apartment early Sunday morning in what is believed to be an overdose. He was 34-years-old.

The New York City Police Department tells DailyMail.com they received a call at 12.15am Sunday morning for a welfare check from Kroll's girlfriend who said she couldn't get in touch with him.

When police arrived at his apartment on Spring Street they found him unresponsive in his bedroom.

A source adds that drugs believed to be cocaine and heroin were also found in the apartment.

His HQ and Vine co-founder Rus Yusupov tweeted his condolences Sunday.

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Colin Kroll, CEO and co-founder of HQ Trivia and previously of Vine, was found dead in his New York City apartment of an apparent overdose at 34-years-old

Police found Kroll dead in his apartment on Spring Street (pictured) shortly after midnight Sunday morning with drugs believed to be cocaine and heroin near by

HQ and Vine co-founder Rus Yusupov pictured with Kroll tweeted his condolences

HQ Trivia host, Sharon Carpenter, took to her social media to express her condolences

Kroll's HQ and Vine co-founder Rus Yusupov tweeted his condolences Sunday

HQ Trivia's main Twitter account also tweeted condolences to Kroll's family

'So sad to hear about the passing of my friend and co-founder Colin Kroll. My thoughts & prayers go out to his loved ones. I will forever remember him for his kind soul and big heart. He made the world and internet a better place. Rest in peace, brother,' Yusupov shared.

One of the app's live game show hosts', Sharon Carpenter, took to her social media to share a snap of the co-founders, herself and fellow host Scott Rogowsky posing at Rogowsky's birthday party.

'I posted this photo just a few days ago. Now, with a heavy heart, I’m posting it again. Thank you for your world-changing creations. A brilliant mind gone way too soon.'

Rogowsky has yet to comment about the incident.

HQ Trivia's Twitter account also shared: ;We learned today of the passing of our friend and founder, Colin Kroll, and it's with deep sadness that we say goodbye. Our thoughts go out to his family, friends and loved ones during this incredibly difficult time.'

Kroll was named the CEO of HQ Trivia in 2015, prior to that he was the co-founder of Vine and did a brief stint at Twitter.

When Twitter purchased Vine, they brought Kroll on board.

However 18 months after being hired with Twitter, Kroll was fired over allegations lodged against him by female colleagues.

His colleagues described him as 'abrasive and disinterested, and said he could be verbally abusive.'

HQ Trivia which had been in the top 10 list of downloaded iPhone games in January had slid to between the top 250 and 500 spot.

Colin (far right) pictured with his family on Christmas Eve of 2015

HQ Trivia is a live game show app in which users compete for cash prizes if they are able to answer all 12 trivia questions correctly

HQ Trivia users compete with other players as part of a live game show. Players who are able to answer all 12 trivia questions correctly stand to win prize money.

Kroll was recently facing a complaint filed with H.R. by an HQ employee for his 'aggressive management style.'

Before he co-founded Vine, Kroll was the Chief Technology Officer for Jetsetter.

From 2007 to 2009 he was the engineering manager at Yahoo.

The Medical Examiner's office will determine the exact cause of death.