The principal of an Ottawa elementary school says city crews working near his school are putting his students in danger.

The charges come after a city crew was operating heavy machinery on a grassy area that backs onto St. Elizabeth Ann Seton School while children were on recess on Tuesday. Although the land is city-owned, the school has an agreement that allows children to play on the fields while they're on recess and lunch.

"It made me sick -- physically sick to walk out and see this situation," said Dwight Delahunt, the school's principal.

Delahunt said he was given no warning about the work, even though it is city policy to inform the school before crews do work on the property. It is also city policy to stay as far away from kids as possible. If a child comes too close, workers are told to shut off their equipment.

But Delahunt said that policy does not go far enough. On Tuesday, he said teachers scrambled to get students away from their usual playing area to ensure their safety.

Delahunt said this is the fourth time this spring that crews have been working on the property while students were on recess or lunch.

Students are now taking the matter into their own hands by writing letters to their councillor and mayor asking for change.

Coun. Jan Harder, who represents the area, said the city and the school board will review the policy. However, she said it's likely the current rules are the best the city can do.

The City of Ottawa has investigated the incident and has concluded the policy currently in place was followed.

With a report from CTV Ottawa's Kate Eggins