The death toll from two factory fires in Pakistan has reached 314, most of them killed by suffocation when they were unable to escape the buildings, officials said Wednesday.

The fires in a shoe factory in Lahore and a garment factory in the southern port city of Karachi, broke out Tuesday night. The Karachi fire killed at least 289 people, while the other 25 deaths were reported at the Lahore factory.

The New York Times reports that officials said panicked workers were trapped inside the Karachi facility, which had only a single exit:

"All the other doors had been locked, a common practice to ensure that workers do not leave the premises before their shift ends.

"The windows of the building were also blocked by metal grills. Many survivors suffered third-degree burns, rescue workers said.

" 'Workers, who were in the basement, died due to suffocation. All exit ways were closed,' Ehtisham-ud-din, the chief fire officer of Karachi, told reporters."

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Source: NPR