Anti-U.S. demonstrations in Afghanistan have erupted in Kabul, the capital, and across the country in a fourth day of protests over the burning of Qurans at a NATO facility.

The crowd of men in Kabul Friday shouted “death to America.”  Officials say police fired into the air to disperse the protesters, wounding at least one.

Friday is the Muslim holy day and the protests began after the weekly prayer services at mosques.

The top U.S. commander in Afghanistan, General John Allen, issued a statement Friday, calling on “everyone throughout the country” to “”exercise patience and restraint” during the investigation into the burning of the Qurans at Bagram airbase.  The statement said witnesses are being interviewed.  The joint investigation team is comprised of members of NATO and the Afghan government.

At least 13 people have died in demonstrations since the protests erupted Tuesday.

U.S. President Barack Obama has sent a written apology to Afghan President Hamid Karzai about the desecration of the Islamic holy book at the Bagram airbase.

The U.S. embassy has urged Americans to avoid any unnecessary movement within the South Asian nation.

On Thursday, NATO officials said an individual wearing an Afghan army uniform shot and killed two coalition soldiers in eastern Nangarhar province during a protests over the Quran burning.

Earlier Thursday, the Taliban issued a statement calling on Afghans to launch attacks on foreign targets in retaliation for the burning of the Muslim holy book.

However, the Afghan delegations assigned to probe the incident appealed to the Afghan people to avoid resorting to protests.

On Wednesday, President Karzai had appealed for calm, saying citizens have the right to protest, but should not resort to violence.

U.S. Deputy Defense Secretary Ashton Carter met Wednesday in Kabul with Afghan leaders, including President Karzai, to apologize for the incident.