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Good morning.

Here’s what you need to know:

Shots are fired, and bots swarm in

• Soon after the mass shooting at a high school in Florida last week, Twitter accounts suspected of having links to Russia jumped on the hashtag #Parklandshooting, posting messages about gun control.

The automated accounts follow a pattern: “The bots focus on anything that is divisive for Americans. Almost systematically,” said an executive at a company that tracks online disinformation campaigns.

• The shooting, which killed 17 people, has left educators grappling with the prospect of becoming first responders or, worse, human shields. One teacher said, “If I go through my college transcripts — master’s degree, doctorate courses, all that — I know for sure there are no courses that say: ‘Shooter on Campus 101.’ ”