DETROIT -

From the city to the suburbs, thieves are targeting homeowners who are cutting their lawns and working outdoors.

In Bloomfield Hills, a jewelry thief robbed one home while an elderly man cut his grass. In Detroit, an armed gunman went after a homeowner who was working his yard.

"They just pick opportunities, and you have to be aware," said Jenny Providence, of Detroit.

It's happening so often that neighborhood watch groups are issuing warnings, telling people only to work outdoors when a family member or a neighbor is available to keep watch.

Providence is taking the advice. Her husband watches out the upstairs windows while she tends to the yard.

"My husband is upstairs looking out that window watching me. We already discussed it, he said, 'You work and I'll watch,' and we do have protection," she said.

It's a crime of opportunity. Some criminals are just riding around seeing who is out. The crimes happen in a split second.

Metro Detroit police records show these types of robberies are on the rise in Wayne, Oakland and Macomb counties.

"You have to be aware of your surroundings. Period," said Providence.