US police assess rise in threat tips after 3 mass killings

In the weeks after three high-profile shootings in three states took the lives of more than two dozen people in one week in August, law enforcement authorities nationwide reported a spike in tips from concerned relatives, friends and co-workers about people who appear bent on carrying out the next mass shooting.Some of those would-be shooters sent text messages to friends or posted on social media that they hoped to one-up previous mass shootings by killing more people.The reasons for the increa