5 stories to follow: Sept. 18

An armed officer who said he is with the Department of Defense, works near the gate at the Washington Navy Yard, closed to all but essential personnel, in Washington, on Tuesday, Sept. 17, 2013, the day after a gunman launched an attack inside the Washington Navy Yard on Monday, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital. (AP Photo/Jacquelyn Martin)

Here's your daily look at five stories we're following today:

1. Gun control: The mass shooting this week at the Washington Navy Yard spurred renewed calls for new gun-control measures. But both Pennsylvania Republican Sen. Pat Toomey and Sen. Joe Manchin, a West Virginia Democrat, who cosponsored a background-check plan earlier this year, said they're unlikely to bring up the bill again.

2.  Pa. schools grading system: Pennsylvania education officials are set to outline a new grading system for the state's public schools today. The new School Performance Profile will replace the "adequate yearly progress" standard and be based on data that includes attendance, standardized testing participation, graduation rates and closing the achievement gap.

3. PATCO escalators: The PATCO board is slated to vote today on a $1.39 million contract to fix broken escalators and elevators at train stations. The new contract comes as the Federal Transit Administration is investigating the escalator and elevators failures, after receiving complaints that the transit agency's service doesn't give the required access to handicapped commuters.

4. Another big Powerball: The jackpot for tonight's Powerball drawing has reached $400 million, the fourth-largest in its history. The three largest jackpots all happened within the past 10 months.

5. Valor awards: More than 50 emergency responders from around the Philadelphia region will be honored tonight at the National Liberty Museum's annual valor awards ceremony.