For the second time in as many weeks, a Twin Cities laborers union claimed Tuesday to have witnessed a child working at a school construction site, this time at Scenic Heights Elementary in Minnetonka.

An employee of Laborers Local 563 said the child, a teenager, told him he was 18, but another worker at the site — whom the child said was his father — admitted he was a minor.

A couple of weeks ago, the group photographed another boy working at a construction site at Cornelia Elementary School in Edina.

The union reported both incidents to the Minnesota Department of Labor and Industry and the U.S. Department of Labor.

"It's becoming clear that these aren't isolated incidents, but rather a disturbing trend of contractors cutting corners and putting children in harm's way," said Tim Mackey, business manager for Laborers Local 563. "Children should be learning in the classroom, not building them."

In the earlier incident, the Edina district determined that the minor accused of working at Cornelia Elementary was related to a subcontractor. It has received assurances from its contractor that no other minors will be allowed on site.

Union leaders said Tuesday that they notified Minnetonka school officials of the incident at Scenic Heights but have not heard back from the district.

The district did issue the following statement: "Minnetonka School District awards construction contracts to the lowest, responsible bidder, including both union and nonunion general contractors. General contractors are responsible for complying with all statutes and regulations in the performance of their work. The District expects all contractors to follow labor laws. Current and past contractors who work for the District follow labor laws and provide high quality work at our schools for the lowest cost."

The school district is adding kindergarten classrooms at Scenic Heights.

The union said it believes the teenage boy at the Minnetonka site was working for a subcontractor. The man who said he was the boy's father said the child was not working on the project.

"But those claims are suspect, since the child looked younger than 17, was carrying a tape measure, and his clothing was spattered with concrete and what appeared to be construction dust," wrote Kevin Pranis, organizing director for the Laborers District Council of Minnesota and North Dakota, in a letter to Minnetonka Superintendent Dennis Peterson.

The union has asked that if the Minnetonka district ultimately verifies that a child was present on the project, it remove all involved contractors.

A spokesman for the union said the group is not targeting school sites on the lookout for child workers. "There's no agenda here," said Robb Leer.