(Harrisburg) -- The mayor of Harrisburg is ordering evacuations of the city’s riverfront streets and low-lying areas. Mayor Linda Thompson says the 6,000 to 10,000 city residents in city flood zones should leave their homes -- or stay at their own risk. City spokesman Robert Philbin says water is rising faster than river crest forecasts are estimating. "If the water is rising in your neighborhood, evacuate. Once you evacuate, do not come back," he says. "Statistically, most injuries and fatalities occur when people enter a flood zone, not when they leave a flood zone. The Susquehanna is expected to crest at 29 feet by late today or early tomorrow. Mayor Thompson is asking downtown businesses to close throughout the weekend. PPL Electric and UGI shut down utilities in low-lying streets along the riverfront in Harrisburg this afternoon. A Red Cross shelter is set up at Harrisburg High School for evacuees.