Shells fired from a mortar-like mechanism near a municipal government building in Istanbul slightly injured three people, the city's governor reportedly said.
Unknown assailants fired the shells from a cemetery near the building that houses the Uskudar district's Parks Department, and one of them hit a truck parked outside the building, the private Dogan news agency cited Gov. Muammer Guler as saying. Others fell short and exploded in the cemetery, the report said.
The assailants used a simple mechanism that worked like a mortar to catapult the shells, Guler reportedly said.
Earlier, the private TV stations CNN-Turk and NTV said the intended target was a military barracks nearby but the shells did not travel far enough.
But Guler said the real target was not clear, Dogan reported.
Thursday's shelling came less than two weeks after two bombs targeting civilians at a packed Istanbul square killed 17 people and injured more than 150 others - the worst such attack in Istanbul in five years.
Official blamed that attack on the Kurdish rebel organization known as the PKK, but the PKK denied responsibility. The rebels are fighting for self-rule in Turkey's east and southeast.
No one has yet claimed responsibility for Thursday's attack.
The three injured people were taken to a local hospital, private NTV television reported, quoting Istanbul police chief Celalettin Cerrah.
On Wednesday night, suspected Kurdish rebels fired a rocket at a police outpost in the eastern province of Mus, killing one officer and slightly wounding three, Bulent Solmaz, a spokesman in the Mus governor's office, told the AP.