Police were informed of an explosion at a park in northern Tokyo on Friday, investigative sources said, though no injuries have been reported.There was a call at around 5:15 p.m. that an object left behind by a man exploded at Shimizuzaka Park in Kita Ward, the sources said.The park is in a residential area about 1 kilometer south of JR Akabane Station.Related coverage:Miyazaki Airport to be checked for more unexploded bombs after blastREAD FULL ARTICLE