Sanaa, Yemen (CNN) -- Gunmen loyal to former Yemeni President Ali Abdullah Saleh attacked the country's main airport with mortars Saturday, forcing authorities to cancel flights, witnesses and officials said.
Two officials at Sanaa International Airport told CNN that the former commander of Yemen's air force had warned he would bring down any civil aircraft departing or arriving the airport unless his demands are met.
The commander, Mohammed Saleh al-Ahmar, is one of several relatives of the former president who were replaced in a major military shakeup. Al-Ahmar refused to give up his post.
Ali Saleh was forced to step down from power in February.
Al-Ahmar, the half-brother of the former president, was given a new position as assistant to the minister of defense in Friday's presidential decree, but has refused to leave his air force post.
The officials said he threatened to cause chaos if three opposition military officials are not removed from their military posts along with him.
The airport was not allowing flights to arrive or depart the country due to the tension, according to security officials at the airport who wished to remain anonymous.
Friday's shakeup was announced in a statement by a spokesman for the Yemeni Embassy in Washington and attributed to current President Abdu Rabu Mansour Hadi.
"President Hadi promised major change in the military, and tonight that promise was delivered," said Mohammed Albasha, the embassy spokesman.
"This is the biggest military shakeup in modern Yemen history."
Another of the sacked Salehs was the former president's nephew, Tareq Saleh, who had been head of the presidential guard.
Two prominent members of Ali Saleh's family remained in powerful military posts however after Friday's shakeup.
They are Brig. Gen. Ahmed Ali Abdullah Saleh, who is the former president's son and head of the Republican Guard, and Brig. Gen. Yahya Mohammed Abdullah Saleh, the former president's nephew and head of Central Security Forces.
Minutes after the military decrees were announced, a senior opposition leader's residence was heavily shelled.
Opposition parties condemned the attacks on the residential compound of Hameed al-Ahmar, president of the opposition Dialogue Committee.
"Attacks on al-Ahmar come in retaliation against the president's orders to remove senior Ali Saleh aides from their military positions," said Fowzy al-Jaradi, the spokesman for al-Ahmar's office.
The military committee, the country's highest security authority, warned all political and military factions to be cautious and urged them to help in defusing the current tension.
Opposition factions in Yemen have refused to participate in the anticipated national dialogue unless complete military reforms take place first.
Anti-government demonstrators demanded last year that all of the former president's relatives be replaced.
After months of massive street protests, Ali Abdullah Saleh finally stepped down in February in exchange for immunity, as part of a power transfer deal brokered by the six-nation Gulf Cooperation Council. However, he remained president of the ruling General People's Congress party.
The restructuring of the military was part of the negotiated power transfer deal and was promised by the new president.
CNN's Mohammed Jamjoom contributed to this report.