TALLAHASSEE, Fla. (AP) — Sorrow is reverberating across the country Sunday as Americans joined a Florida community in remembering the 17 lives lost three years ago in the Parkland school shooting massacre. President Joe Biden used the occasion to call on Congress to strengthen gun laws, including requiring background checks on all gun sales and banning assault weapons. The president said there was no time to wait. Florida Gov. Ron DeSantis ordered flags be lowered to half staff from sunrise to sunset across the state to honor those who perished when a former student of Marjory Stoneman Douglas opened fire on campus with an AR-15 rifle on Valentine’s Day in 2018.