Jerusalem (CNN) -- A small pipe bomb, hidden in a garbage bag, exploded Sunday morning -- injuring one person moderately, police in Jerusalem said.
The bomb went off as a sanitation worker collected the bag, said police spokesman Mickey Rosenfeld.
A second worker at the scene was not hurt, Rosenfeld said.
Police were investigating the incident and did not immediately have a motive.
In an unrelated incident, the Israeli military said it targeted a "terror tunnel" and two terror activity sites in Gaza on Saturday night.
The air force attack came after militants fired rockets into Israeli territory earlier Saturday, the military said.