1 of 10
More than 20 inmates in a Philippines prison have been killed after police stormed the building following an attempted break-out involving members of militant Muslim group the Abu Sayyaf.

2 of 10
At least five people, including three guards, were killed in the initial jailbreak attempt on Monday.

3 of 10
A standoff ensued, during which hundreds of snipers and police gathered at the prison.

4 of 10
Police tried to negotiate the conditions of a surrender, and the inmates at first seemed willing to come to an agreement.

5 of 10
As the standoff continued towards nightfall, a large crowd gathered outside the prison.

6 of 10
Early on Tuesday morning, elite police commandos finally stormed the prison, after a government ultimatum expired.

7 of 10
Teargas was fired into the building - police and medics can be seen covering their faces.

8 of 10
Water was later sprayed on inmates to ease the effects of the teargas.

9 of 10
At least 20 prisoners were killed, including three senior Abu Sayyaf leaders. Several others were injured.

10 of 10
Other inmates were rounded up, before being escorted back to their cells.