Explainer-How gun laws in Pennsylvania, where Trump was shot, compare with other US states

By Tom Hals

(Reuters) - The shooting of former President Donald Trump in Pennsylvania on Saturday, allegedly by a 20-year-old gunman, has put the spotlight on the state's firearms laws. Below is a look at Pennsylvania's gun laws how they compare to other states.

ARE PENNSYLVANIA'S GUN LAWS CONSIDERED RESTRICTIVE?

The state is ranked 16th in the nation for the strength of its gun-control laws by advocacy group Giffords Law Center. The organization cited the state's requirement for background checks as one of its strengths. The state's Democrat-controlled House has passed multiple gun control bills in the past two years, including a ban on untraceable "ghost" gun parts. Those bills have stalled in the Republican-controlled state senate.

DOES PENNSYLVANIA RESTRICT ASSAULT-STYLE WEAPONS?

Pennsylvania does not ban the AR-15 military-style weapon used in many mass shootings including the Trump attack. The neighboring states of Maryland, New York and New Jersey are among the nine states that currently ban the sale of such weapons, according to Everytown for Gun Safety. The U.S. Supreme Court declined to hear challenges to bans on the weapons in Maryland and Illinois this year.

WHAT ARE THE STATE'S AGE LIMITS AND STORAGE REQUIREMENTS?

Thomas Matthew Crooks, the 20-year-old alleged shooter, was over the legal age of 18 to possess a long gun in the state. The firearm in Saturday's attack was purchased by his father, according to officials. It is not currently known if he had permission to use the firearm. Twenty-five states and the District of Columbia require locked storage of guns, although not Pennsylvania, according to the American Academy of Pediatrics.

DOES PENNSYLVANIA HAVE A 'RED FLAG' LAW?

Trump has been a polarizing figure in American politics, but it is not known the motive behind the attack or whether the shooter was tied to an extremist group or ideology. Pennsylvania lacks an extreme risk protection order, known as a red flag law, which allows family members or law enforcement to bar temporary access to firearms for an individual at risk of harming themselves or others. Twenty-two states and the District of Columbia have such laws, according to the Giffords Law Center.

WHAT LIMITS DOES THE STATE PLACE ON AMMUNITION PURCHASES?

The shooter reportedly purchased 50 rounds of ammunition just prior to Saturday's attack, according to CNN, citing a law enforcement official. Pennsylvania does not limit the number of firearms or the amount of ammunition an individual can purchase and the state does not perform background checks on ammunition purchases, according to Adam Garber of CeaseFirePA, which advocates for greater gun restrictions. Nine states and the District of Columbia regulate ammunition sales, according to the Giffords Law Center.

COULD AUTHORITIES CHARGE THE FATHER?

The shooter, who was killed in the attack, used his father's gun, according to officials. If authorities wanted to investigate the possibility of charging his father, they would have to answer many questions, according to Garber. Investigators would want to determine if the gun was secured, if it was shared with the shooter, if the father knew of his son's intention and why the father purchased the firearm. Garber said he was unaware of a parent of an adult shooter being charged in a shooting.

Michigan parents of a school shooter were sentenced in April to between 10 to 15 years in prison for their role the attack by their son, who was 15 at the time.

(Reporting by Tom Hals in Wilmington, Delaware; editing by Amy Stevens and Alistair Bell)