One dog had to be put down and another was seriously injured after they were allegedly attacked by three pit bulls in southeast Calgary.

Calgary animal services have seized three pit bulls after a dog and a 13-year-old girl were bitten while walking in a southeast dog park.

The incident reportedly occurred in the Millican Ogden Outdoor Swimming Pool on Monday afternoon.

A 13-year-old girl and her 14-year-old brother were walking their dogs when they came across three pit bulls, which were all leashed, being walked by one man.

When the dogs approached one another, the pit bulls apparently attacked.

One of the other dogs recieved three deep holes in its chest cavity and late had to be put down.

The other suffered a bad bite that required 16 stitches.

The girl suffered a bite to her hand while trying to separate the animals.

Animal and bylaw services are investigating the incident.

They say the dogs will undergo a behaviour test before their fate is decided.