TEL AVIV—A suspected Arab gunman killed at least two people in an attack at a bar on a main Tel Aviv boulevard on Thursday, police and hospital officials said, the latest in a string of deadly street assaults that have shaken Israel. Mayor Ron Huldai said the shooting, at the start of the weekend in Israel, was suspected to have been carried out by an Arab attacker with “nationalistic” motives who entered a pub and opened fire. Three other people were seriously wounded. Hundreds of emergency responders arrived on the scene and police, searching for the shooter, told residents to stay indoors. Television footage showed armed officers running down Dizengoff Street, a crowded street of shops, bars, and restaurants, and side alleys trying to track down the attacker. A police helicopter shined a spotlight from above. “A terrorist opened fire at short range and then fled on foot. Several people …