Video obtained by Reuters shows protesters hurling rocks at a military convoy near the town of Kobani, Syria.
The Syrian Observatory for Human Rights, which monitors the war from Britain, said that two were killed and seven injured.
But a witness told Reuters that only three people were wounded at the scene, without mentioning any dead.
The witness said the soldiers first fired their weapons into the air in an attempt to disperse the crowd, before firing at the protesters.
Tear gas was also used, according to the witness.
A statement by the Turkish Defense Ministry said a patrol was conducted "with due care and diligence for the safety of both civilians and our military personnel despite provocation by terrorists." TASS news agency cited Russia's Defense Ministry as saying that Turkish forces and Russian military police conducted a patrol north of Kobani without mentioning a shooting incident.