ISLAMABAD, Pakistan — Dozens of tanker trucks carrying fuel to Afghanistan for NATO troops were torched near Quetta in western Pakistan on Wednesday, the third major attack on supplies since Pakistan closed a border crossing to Afghanistan a week ago and the first at the only checkpoint that remained open.

The latest sabotage came as American officials for the first time offered an explicit apology to Pakistan over a shooting that led to the closing of the other border crossing, possibly laying the ground work for its reopening.

At least one person was killed in the Quetta torchings after three carloads of gunmen fired at the tankers and then burned them, the police said.

“According to eyewitnesses and initial reports some terrorists came on vehicles a few minutes before morning prayer and started firing and then burned some of the tankers,” said Hamid Shakeel, the deputy inspector general of the Quetta police.