If the area is (1) open to the public, and (2) people are there voluntarily then it would be permissible to capture and publish images. However, it would be prudent not to make anyone uncomfortable.
Kinds of consent
Signage or notification is not required in public spaces. However, best practice would suggest photography signage be posted, unless the image captured is newsworthy or for a journalistic reason.
Options to publish
If in a public area and consent has not been obtained and a person’s image has been captured incidentally, it may be published. However, best practice would be to blur the face or other recognizable traits, especially of children, so that the person is not identifiable.