BEIRUT -- A Syrian opposition coalition on Sunday called on Turkey to investigate the deaths of at least eight Syrian refugees, including four children, who were allegedly shot dead by border guards the night before while trying to cross the frontier.

A suicide blast meanwhile targeted the entrance to a park in the Syrian city of Qamishli, which is shared between government and Kurdish forces, killing three people, an hour after a memorial was held there for victims of the 1915 Armenian genocide.

"Had the bombing taken place earlier, there would have been a massacre," Qamishli resident and writer Suleiman Youssef told The Associated Press via telephone. Qamishli lies on Syria's northern border with Turkey.

A statement put out by the National Coalition of Syrian Revolution and Opposition Forces accused Turkish border guards of firing at a group of civilians trying to cross from Kherbet al-Jouz in northwestern Syria into Turkey's Hatay province, killing 11.

The Coalition, which relies on Turkish political and financial support, said the incident "clashes with the generosity displayed by the Turkish government and brotherly people toward displaced civilians."

The Britain-based Syrian Observatory for Human Rights put the toll at eight dead. The Local Coordination Committees, an activist network, said at least one of those trying to cross was from Jarablus, a northern Syrian town under Islamic State control.

A senior Turkish official said "we are unable to independently verify the claims" regarding the shooting, but said authorities were investigating.

"Turkey provides humanitarian assistance to displaced persons in northern Syria and follows an open door policy -- which means we admit refugees whose lives are under imminent threat," the official said on condition of anonymity in line with government regulations.

The Syrian war has pushed over 2.7 million refugees into Turkey, according to the U.N. Turkey has tightened security along its border in recent months to prevent further inflows.

Associated Press writers Albert Aji in Damascus, Syria, and Dominique Soguel in Istanbul contributed to this report.