LAHORE, Pakistan - Pakistani authorities said at least 11 people have been killed and 50 others injured in a massive suicide bombing in the city of Lahore in eastern Pakistan.

The bomber drove an explosives-laden truck into the main gate of a building used for interrogation by the Pakistan's Federal Investigation Agency, heavily damaging the building and several nearby structures.

Rescue workers were trying to reach people trapped under the debris in the Model Town neighborhood. The massive bomb left a large crater outside the building.

"It was a suicide attack," Pervaiz Rathore, an official with the Pakistani police, told reporters.

"We have heard that 40 to 50 people were in the [agency's] building when the incident happened," he said.

Some officials said the bombing typified al-Qaeda-backed attacks by the Pakistani Taliban.

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AP, AFP and Reuters contributed to this report.