At least eight people have been killed and 38 injured in a crush outside an Africa Cup of Nations football match in Cameroon.
Videos showed screaming fans being crushed at an entry gate to the Olembé stadium in the capital Yaoundé.
Witnesses described chaotic scenes outside the ground as thousands of fans struggled to get access.
Two boys, aged eight and 14, are among the dead, and seven people were seriously injured.
Cameroonian President Paul Biya ordered an investigation into the "tragic incident". The Confederation of African Football (Caf) has also launched its own investigation, and says a minute's silence will be observed at future matches as a mark of respect to those who died.
Officials say about 50,000 people tried to attend the match on Monday.
The stadium has a capacity of 60,000 but it was not meant to be more than 80% full for the game because of Covid restrictions.
Nick Cavell, a producer for BBC Africa Sport, was at the match and says news of the crush did not seem to filter through to the crowd until there were reports on social media.
Images on social media show fans clambering over fences, rushing past checkpoints and trampling on unconscious supporters. Others show some trying to resuscitate their fellow fans.
Danish journalist Buster Emil Kirchner described seeing "a lot of chaos" as fans clamoured to enter the ground through a single open gate.
"It was hectic - people running, people climbing fences, people breaking through the barricades," he told the BBC.
Another journalist, Leocadia Bongben, saw a commotion coming from one of the fan zone areas outside the stadium.
"People started shouting," she told the BBC's Newsday programme. "A minute after that an ambulance came to the stadium, but when we got to the place the police would not allow us to get close to where the stampede was.
"It's really quite a sad situation that people go to watch a game and they end up dying there."
Some of the injured were in a "desperate condition", nurse Olinga Prudence told the Associated Press.
By Piers Edwards, BBC Africa Sport, Yaoundé
Cameroon is football-mad and has not hosted an Africa Nations Cup in 50 years, so crowds flocked to the stadium to see the biggest game of the tournament so far. The problem is, 30 minutes before kick-off, only one gate - the south gate - was open.
A bottleneck formed, with one eyewitness saying fans with tickets were waving them in the air trying to gain access, frustrated with the slow speed of entry. Fans without tickets were also in the crowd, trying their luck.
Fans need a negative Covid test to get into the stadium, which can only delay things - but this is not done by the gates - and separate sources I've spoken to do not believe it had a major bearing on the stampede.
Security at the Afcon stadiums could be better - there is a significant police presence but it is not as organised as it could be. Some gates are flimsy with temporary fencing supported by breeze blocks that can be pushed down - though this was not the case with the south gate, where people were trampled and pressed against fences in the crush.
Vanessa Tchouanzi told Reuters news agency she saw her friend get knocked over and killed by a rush of people "coming in in droves".
"She couldn't take the shock, the weight of all those people," she said.
Football's world governing body Fifa said the "thoughts and prayers of the global football community" were with those affected.
Caf President Patrice Motsepe said no more tournament matches would take place at the stadium until there was an "absolute guarantee" fans would be safe.
"Clearly there were failures - there were things that should have been foreseen," Mr Motsepe told a press conference.
The African football body said Sunday's quarter-final would now be moved from the Olembé stadium and held instead in another stadium in the same city - the Ahmadou Ahidjo.
Six people are reported to have been killed and dozens hurt in a crush outside a stadium hosting an Africa Cup of Nations match in Cameroon.— Charles Ayitey (@CharlesAyitey_) January 24, 2022
Video footage showed football fans struggling to get access to the Paul Biya stadium in a neighbourhood of the capital Yaounde. pic.twitter.com/a6WLbFZORj
After a low turnout at the first round of matches of the continent's top football tournament, the Cameroonian authorities have organised mass transport and given out free tickets to lure fans to attend.
The Olembé stadium, officially called the Paul Biya stadium but dubbed "Olembé" after the neighbourhood it occupies, is the largest in Cameroon and opened last year. It was scheduled to host three more matches, including the final.
Cameroon was supposed to host the Africa Cup of Nations in 2019, but was stripped of the event amid concerns over delays in building stadiums and infrastructure.
Monday's last 16 match between Cameroon and Comoros took place despite the incident and ended with a 2-1 win for the hosts.
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