A three-alarm fire that damaged seven Walnut Street row houses in York City on Monday has been ruled arson. Eleven people were displaced by the deliberately set fire that caused $200,0000 in damage, said David Michaels, chief of York City Fire/Rescue. No injures were reported, but White Rose Ambulance medics gave oxygen to two dogs rescued from one of the homes, Michaels said. The dogs - a boxer and a beagle - are now doing fine, he said. Crews were dispatched to the blaze about 1:15 p.m. and had the fire under control about two hours later, according to a fire official.