Hunt for survivors in Pemex building - "Mexico City blast"

Rescuers have been working overnight to find survivors trapped after a deadly blast at the Mexico City headquarters of the state oil company, Pemex.

Some 500 rescuers helped by dogs are searching the building for a number of people thought to be trapped by a blast that killed 25 people and injured 100.
Relatives of employees have gathered in search of information - some trying to reach loved ones via mobile phone.
The cause of the blast is under investigation, Pemex says.
'Full weight of the law'

  Relatives of employees gathered desperate for information about their loved ones

Thursday afternoon's explosion in the lower floors of a building adjoining the 54-storey Pemex skyscraper happened as shifts were changing, making the area particularly crowded.
Debris from the blast spread out on to the street in front of the building.
Red Cross ambulances and helicopters were shuttling the injured to hospital, while firefighters and soldiers dug through chunks of concrete with a crane to reach trapped survivors.

Will Grant BBC News, Mexico City

The Pemex building in the north of Mexico City is surrounded by large numbers of federal police and paramedics. Sniffer dogs are being used to look for people trapped under the rubble.
Mexico City is used to earthquakes, and the emergency services seem well prepared for this type of disaster.
The skyscraper withstood the blast too, with most of the damage confined to the ground and first floors. But night has set in now in the Mexican capital, further complicating the search.
Some family members of missing workers are gathered outside the Pemex building for news of their loved ones, while others have travelled directly to the hospitals.
The authorities and paramedic teams are releasing information at regular intervals but the exact cause of the blast may still take some time to be confirmed. This is now by far the worst explosion in Mexico City for almost 30 years.

One distraught relative, Ana Vargas Palacio, told Associated Press she had spoken to her husband, who works in the building, two hours before the blast.

"I called his phone many times, but a young man answered and told me he found the phone in the debris," Ms Vargas said.
Police cordoned off the streets around the building, which is located in a busy commercial area of Mexico City.
Rescuer German Vazquez Garcia told AP there was "a lot of risk" involved in the search.
President Enrique Pena Nieto and Mexico City Mayor Miguel Angel Mancera, who visited the scene of the blast, said Pemex rescue and security teams were working alongside city authorities to help the injured.
Mr Pena Nieto said: "We have no conclusive report on the reason [for the blast]. We will work to get to the bottom of the investigation to find out, first, what happened, and if there are people responsible in this case, that we apply the full weight of the law against them."
The BBC's Will Grant, at the scene, says this is the biggest explosion to hit Mexico City for 30 years.
Pemex says its operations will continue to run normally - and commercial and financial obligations will continue to be met - despite the blast.
The company has experienced a number of fatal accidents in recent years.
Last September, 30 people died in an explosion at a Pemex gas plant in northern Mexico, thought to have been caused by a build-up of gas.