A man has been approaching juveniles in a dark blue pickup truck in Loudoun County, and police are asking for help in finding a suspect.

The man has been described as 50-60 years old, with white or gray hair and wrinkles. He drives a dark blue pickup truck made in the late 1990s or the early 2000s.

He's been linked to at least three incidents in the county in the past week, authorities say.

The most recent happened Tuesday evening along Algonkian Parkway. The man approached a group of people walking on the parkway's footpath but drove away a short time later.

A day earlier, a female 5th grader had been approached by a man and truck with a similar description after she got off a school bus near Hollymead Place in Sterling. The man asked her if she wanted to go to Starbucks. When she didn't respond, he drove away, authorities said.

The earliest known incident happened the afternoon of Sept. 5 when a woman saw an older white man watching her as she loaded groceries into her car. He followed her to her home and parked nearby, but drove away as neighbors returned home.

Police are asking residents with any information to call Detective Tresselt or Sergeant Hunt at 703-777-0475. They can also submit tips by emailing crime.info@loudoun.gov.