You still need to do due diligence and attempt to find the owners. Legally you would be responsible if someone else actually missing these dogs and you just "give" them away. Also, keep in mind, anything can happen. Dogs with no food catching skills get skinny quick....if somebody lost these dogs a couple weeks ago, they would be in poor condition. You need to get them scanned, post ads and call your local shelter. When I was in Southern California working for animal control, the law required people to hold any 'stray' for 30 days along with advertising them so owners can find them. Only after the 30 days are you able to keep them or rehome them. The holding period if the dogs are impounded is much shorter as it is so much easier for the owner to find them that way.
We also used to regularly scan dogs and call the owner only to find that the dog had been missing for A LONG TIME. Because people find dogs and then just give them away.....being in poor condition means nothing about the kind of home they had.....