The Latest: Putin says terror attack, other causes possible

ST. PETERSBURG, Russia (AP) — The Latest on the explosion on a train in the Russian city of St. Petersburg (all times local):
4:35 p.m.
Russian President Vladimir Putin says investigators were looking into whether the St. Petersburg subway explosion was a terror attack or if there might have been some other cause.
He says: “Law enforcement agencies and intelligence services are doing their best to establish the cause and give a full picture of what happened.”
Putin happened to