Aftermath of the Pemex explosion in Mexico - in pictures

A Mexican army officer guards the Pemex building Photograph: Jose Mendez/EPA

A worker from the state-owned oil company Pemex keeps journalists back after the explosion Photograph: Eduardo Verdugo/AP

Paramedics treat injured people in ambulances outside the building Photograph: Zuma/Rex Features

Rescue workers prepare to search for victims Photograph: Yuri Cortez/AFP/Getty Images

Rescue workers, firefighters and military personnel search for survivors Photograph: Eduardo Verdugo/AP

Authorities block access to the affected zone of the Pemex headquarters Photograph: Jose Mendez/EPA

Rescue workers search for casualties Photograph: Yuri Cortez/AFP/Getty Images

An injured person is carried into an ambulance Photograph: Eduardo Verdugo/AP

A helicopter flies over the building
Photograph: Zuma/Rex Features

An injured woman is helped from the building Photograph: Victor De La Cruz/Zuma/Corbis

Blown-out windows after the explosion Photograph: Zuma/Rex Features

The Mexican president, Enrique Peña Nieto, talks to the media during a visit to the scene of the explosion Photograph: EPA

Police block a street leading to the headquarters Photograph: Tomas Bravo/Reuters

A rescue worker walks past debris piled outside Photograph: Reuters