You probably know this, but if the person who picked up the dog needs to get him to a shelter soon, St. Hubert's is responsible for animal control in Maplewood.
Other places to post about the dog, besides the usual neighborhood Facebook groups:
https://www.facebook.com/groups/547507072078678
https://www.facebook.com/essexcountynjlostpets/
and Nextdoor, of course.
Thank you for looking after this stray.
Thank you for the info. We did end up calling the police and they are going to get the dog to St. Hubert's. I will post in those other places, too.
A large black male Lab mix was found at about 2:15 running loose on Springfield Avenue. The man who I helped catch the dog has him now and I am in contact with him. I'll try to get a photo to add later.