A large fireball was seen crossing the Siberian sky on June 20, 1908 before an eruption six miles above ground flattened trees (right) and left charred reindeer carcases. Italian scientists spent 21 years researching the so-called Tunguska event, claiming the blue-water Lake Cheko (left) filled a 'missing' impact crater - giving rise to the theory that the phenomenon was caused by a meteorite. But a new study by Russian geologists suggests the idea is flawed, meaning the huge blast - which lit up the night sky in Europe and even America - is still a mystery, according to reports in Moscow. Experts have not ruled out the possibility a meteorite caused the explosion and have yet to put forward an alternative reason. Outlandish theories in the past have included a massive volcanic eruption, a comet mainly composed of ice rather than solid space rock, a black hole colliding with Earth and even aliens shooting down a meteor from a UFO in order to save Earth.

The final moments of El Chapo Guzman, before he was extradited from Mexico to the US to face trial for drugs charges, have been released. Footage shows Guzman nervously pacing around his cell and looking at the CCTV camera (right) before being put on a plane to New York (inset). The 61-year-old is accused of having imported and distributed around 200 tonnes of cocaine from South America to the US, as well as tonnes of cannabis, heroin and other drugs.

Staff operating emergency hotlines allegedly did not take seriously early telephone calls reporting the disaster in Italy's Gran Sasso national park on Wednesday. As a result, the rescue operation only got into gear some 2.5 hours later, with the first rescue team arriving by ski 11 hours after the catastrophe because the roads were impassable. So far six bodies have been discovered while 23 people are missing and nine have been found alive. But emergency crews (left and top right) were cheered today by the discovery of three puppies (bottom right) who had survived for days under tons of snow - giving them new hope for missing guests.

Mr Erbil is a gathering of Kurdish men who are widely regarded as Iraq's first gentleman's club and have done away with the traditional tatty outfits of the area and replaced them with snappy suits, perfectly-manicured beards and sharp hairstyles. Usually synonymous with constant and bloody battles with terrorists from Islamic State, their region of Northern Iraq has been plagued by civil war, but the pin-ups want to change that. The group of well-groomed hipsters are attempting to change the way people perceive Iraq by giving it an injection of style with a new clothing brand.

Riot police have been sent into Alcacuz jail in Brazil, where 26 inmates have been murdered in two weeks, has been 'taken over' by warring gangs who behead their enemies and take guards hostage. Horrific footage from the aftermath of the riot in Alcacuz Penitentiary, the largest prison in the city of Natal, showed the severed heads of gang members strewn across the prison yard, their blood congealing with the dust underfoot. From elaborate jailbreaks to violent clashes and even rumours of executions being filmed inside its walls, Alcacuz has come to represent the country's crumbling prison system, where 140 have been killed since the start of the year. One of the inmates was killed in the riots last Saturday (bottom right). In 2015, guards seized mobile phones, knives and narcotics (top right) while members of Red Command were photographed when they were arrested (left).

Survivors of a plane crash that wiped out nearly a whole Brazilian football squad watched their team's first game since the disaster today. New Chapecoense players - many on loan from other clubs - took to the field of their home stadium for a friendly against Brazilian league champions Palmeiras. The match was the final tribute to the 19 players and 24 other club members who perished in the tragedy two months ago as the team travelled to play in the final of the Copa Sudamerica in Colombia. Among the spectators was Chapecoense goalkeeper Jackson Follmann, who was one of only six to survive the crash which killed 77.