PESHAWAR, Pakistan — Amid a wave of bombing attempts in this northwestern Pakistani city on Thursday, a bomb rigged to a timer exploded inside a passenger van, killing seven and wounding six, the police said.

Although the attack was the only one of eight attempted bombings to succeed here, the police said, the mass of attempts pointed to a concerted effort by militants to intensify their attacks on government targets.

“The bombs were intended to destroy an electrical tower, and to target police and a convoy of the law enforcement agencies,” said Shafqat Malik, the head of the Peshawar bomb disposal unit, noting that the bombs all had “a level of sophistication.”

“The bomb that went off was to target civilians. Imagine what would have happened, had they all gone off,” he said. “Today was the worst day in my professional career.”