Q:

What should I do when a new user posts a lot of low quality, late answers to old questions, at the same time?

On July 22, 2017 a new user posted short, not very helpful, late answers to approximately 14 questions. It took place between 22:54 utc and 23:59 utc. 
I first noticed the pattern because they all appeared on the active page. Also, I was the author of some of the posts, so I was notified in my inbox that there had been activity on those posts. 
They began appearing in the review queues, mostly “late answer” and “very low quality.” By then I had figured out what happened, but didn't know what to do. The posts I read weren't vulgar or destructive, and some even looked like a genuine attempt at answering, which actually made it more confusing.
I was considering the following options:

Flag one post immediately with a note to the moderators asking them to review all of the posts.  
Ping a moderator from the chat room  
Choose the “recommend deletion” option for those in the very low quality queue  
Downvote where I thought appropriate, and take no other action  
Try to help the OP improve the answers or teach them how the site works. I noticed one of our very kind experienced users was doing that.  
Leave them all alone and if they hadn't been handled by a mod or other community members by the morning, flag for a moderator

The only action I took was voting to delete two of them. 
When I returned to the site about ten hours later, all the posts and the user had been deleted. 
In general, what would be the correct course of action in a situation like this? 
In this particular case, what was the process that took place between the postings and deletions? I'd like to know the steps that were taken, so I can learn. Most of the deletions are credited to Community. What does that mean? 

A:

When I logged on to find ab2's alert in chat, I checked the flags, and not only were there flags against all the posts by that unregistered user account, there were also ones under two more unregistered accounts which were obviously the same person.
I think in total there were 2 posts that may have been trying to answer, but the majority seemed only lightly related to the subject, or possibly a grab of the first google answer to each question.
This behaviour is somewhere between spamming and very low quality, so as this user had not had any other activity aside from this slew of bad posts, I accepted the flags and deleted the user accounts.
Remember, it is always fine to flag if something needs mod attention - and enough flags will sort the problem even without a mod - but if you think it is just poor quality, a downvote works :-)

A:

I may have been the first user to notice the answers -- I don't remember seeing any downvotes or comments on them when I saw them.  I commented on one (Sue's elf-owl question) because the answer was on point, and was researchable (and although wrong, could have been a good answer if properly researched). I then saw the others, and didn't know what to do, mainly because I thought this might be only the first wave, and many more were on the way.  So I decided to both (1) stick my finger in the dike (downvote, and flag as VLQ or Not an Answer, and comment on the commentable) and (2) to call in the cavalry (aka Rory) via Chat.  A few others later commented, downvoted and flagged.  By 07/23 morning my time (EDT), Mr. Clean (aka Rory) had cleaned up. 
Sorry for mixing metaphors, but what's the good of speaking English if you can't play with it? 

