Tuesday's top 5 headlines: what you should know

At least 23 people are dead in Italy following a head-on collision of two commuter trains in the southern region of Puglia. Railway police Commander Giancarlo Conticchio told Sky TG24 said that the final toll could still be higher. President Obama crafted a touching speech to the Dallas community just a few days after a sniper attack left five police officers dead. "I understand how Americans are feeling. But, Dallas, I'm here to say we must reject such despair. We know that the overwhelming majority of police officers do an incredibly hard and dangerous job fairly and professionally. They are deserving of our respect and not our scorn." After 14 months of policy clashes, Bernie Sanders endorsed Hillary Clinton for the Democratic presidential nomination at a campaign event in New Hampshire, on Tuesday. The makers of Pokémon Go were forced to make emergency fixes to the game because the app gave the company an unprecedented level of access into players' personal lives. Pokémon Go app gets "full access" to your Google account which is something most apps don't dare demand. Donald Trump has narrowed his vice presidential search to three options, an adviser tells U.S. News. Mike Pence, Michael Flynn, Newt Gingrich are Trump's finalists for vice president.