A mysterious underground bunker is making international headlines after its discovery just a few hundred metres from a Pan Am Games venue.

The bunker was discovered on Jan. 14, just south of the courts at the Rexall Centre, also known as the Canadian Tennis Centre, where the Pan Am tennis competition will be held this summer.

Police are still trying to find the builder or builders, but said that the bunker wasn't thought to pose a public safety threat.

"I don't have any evidence that suggests criminality at this point, but bear in mind I don't have the intent behind this at this point. That could change. I'm open to anything right now," Toronto Police Deputy Chief Mark Saunders told media on Tuesday.

The mysterious "tunnel to nowhere" was trending on Twitter across Canada, with #torontotunnel and #YorkUtunnel among the most used hashtags in the country on Monday and Tuesday.

The story was picked up by media organizations outside of Canada, including CNN and ABC News in the U.S., and BBC News and The Guardian in the U.K.

"A big hole in the ground discovered near a venue for the 2015 Pan American Games in Toronto has stumped authorities looking into it," CNN's Ray Sanchez wrote. 

"Toronto Police Stumped by Mysterious Tunnel," ABC's headline read.

"Toronto police investigate mystery tunnel to nowhere," BBC titled a story that questioned the bunker's purpose. 

The Guardian looked at different theories: "Toronto mystery tunnel: #terrortunnel, drug lab or something else entirely?"

The bunker was also featured in the World section of Myanmar International TV's website in Myanmar, listed between a fatal bombing in Nigeria and a story on lionfish in Florida. 

Le Figaro in France questioned whether the bunker could be a survivalist's shelter or a criminal's hideaway.

Corriere Della Sera, in Italy, wrote about the poppy found on the wall of the bunker, explaining to readers that synthetic poppies are worn on Remembrance Day in Canada.

Buzzfeed included a tweet by Toronto Police Staff Sgt. Chris Boddy that asked, "If you built a tunnel near the Rexall Centre in #Toronto give us a call, k?" 

Gizmodo wrote: "Secret Mystery Tunnel Discovered in Toronto – Is Drake Involved?" 

The story was even picked up by American fiction author Stephen King, who took to Twitter to share his theory: "Okay, Mystery Tunnel solved. A wormhole kind of thing. Aliens were going to use it to watch tennis at the Rexall Centre without paying."

Police told media that they don't know what the builder or builders' motive was, but do not believe any criminal activity was intended.

The investigation is ongoing, and police ask that anyone who saw something suspicious in the area, or saw someone with building materials, is asked to contact officers at 416-808-3100, or Crime Stoppers anonymously at 416-222-8477 (TIPS).