A "powerful" blast has been heard in the Swedish capital, Stockholm, eyewitnesses told local media. The area has been cordoned off by police who suspect the explosion was caused by a gas leak.

The blast which was described by witnesses as “powerful” occurred on Brännkyrkagatan street at 11:40 am local time, Aftonbladet newspaper reports.

URGENT: RT stringer in #Stockholm confirms blast, says gas leak suspected https://t.co/tgPS2ZLhtS — RT (@RT_com) November 6, 2015

Windows were shattered in a nearby house, however, the apartment's owner told Expressen.se this is unrelated to the blast.

READ MORE: Stockholm ‘blast’ was actually man doing DIY who… dropped his drill?

“It isn’t clear what happened,” Stockholm police official Albin Näverberg told Aftonbladet.

He told local media that police are looking into the causes and suggested that there could have been a gas leak.

Police raid on the building next to shop! Hope everything is okay -but would love to get into my shop! 🙏 #mrgill #mrgilllego #brännkyrkagatan #södermalm #stockholm A photo posted by MrGill (@mr_gill_stockholm) on Nov 6, 2015 at 3:32am PST

“There was a small blast in the south part of the center, no one was hurt. They suspect [it was] a gas leak,” said RT's stringer in the Swedish capital.

Stockholm police have contacted the owner of the apartment where the blast happened. “There are no signs of a crime,” the local police department said on its website.