While it was hard to immediately determine the extent of the damage and destruction, the resounding sounds of huge explosions heard around Sanaa on Friday night suggested that the Saudi-led strikes were taking a toll.
The strikes' target is Houthi rebels, a Shiite Muslim minority group that has taken over the capital and, on Wednesday, captured key parts of the Yemeni port city of Aden. Aden was where President Abdu Rabu Mansour Hadi had moved because of the rebel advance.
Hadi has since left Yemen, and on Friday he'd arrived in Egypt for a summit of Arab League representatives. Many nations in the Arab League are now participating in the armed effort against the Houthis and presumably to return Hadi to Yemen as its leader.
While he's not in Yemen, the fierce fighting there continues.
Not surprisingly, the Houthis are bearing the brunt of the bloodshed -- and not just in Sanaa.
That includes at least 10 killed in the northwestern province of Saada, home to the Houthi's leader Abdul Malik Al Houthi, Houthi commanders said. More than a dozen more people were wounded, as 15 locations saw airstrikes.
Five Houthis died were hurt in an attack by fighters loyal to Hadi on a Houthi post about 6 miles (10 kilometers) outside Al Anad airbase, two security officials in Lahj province said. That's where U.S. Special Operations Forces involved in fighting al Qaeda in the Arabian Peninsula had been based as recently as this month.
Hadi has also ordered the closure of all Houthi-controlled media -- including Yemen TV and Saba TV.
The Houthis, though, responded by raiding two TV channels and the prominent Al Masdar newspaper.
Al Jazeera's office in Sanaa was also targeted, with Houthis looting security cameras and damaging equipment, the Qatar-based network said.
The nations stepping into Yemen's civil war are predominantly Sunni Muslim, and they are working to rescue a government that has strong Sunni support.
The Houthis are allied with majority Shiite Iran.
Saudi Arabia, the largest contingent in the intervention dubbed al-Hazm Storm, considers the Houthis to be proxies for the Shiite government of Iran and fear another Shiite-dominated state in the region.
"What they do not want is an Iranian-run state on their southern border," CNN military analyst Lt. Col. Rick Francona said of the Saudis.
Call for help
The kingdom says Hadi, who is out of the country, pleaded for military intervention in a letter.
"I ask you, based on the principle of self-defense in Article 51 of the Charter of the United Nations, and on the basis of the Charter of the Arab League and the treaty of joint Arab defense, to provide instant support by all necessary means, including military intervention to protect Yemen and its people from continuous Houthi aggression," read the letter, which was posted by Saudi Arabia's Foreign Ministry.
U.S. Secretary of State John Kerry said Thursday that the United States commends the military action and is supporting it through intelligence sharing, targeting assistance and logistical support, a senior State Department official said.
Houthis cut off
The other nations participating in the military action are the United Arab Emirates, Kuwait, Bahrain, Qatar, Jordan, Morocco, Sudan and Egypt, a Saudi adviser has said.
The adviser also included Pakistan, saying its military was offering naval support. But on Friday, that country's Defense Ministry said it had only vowed to defend Saudi Arabia, according to a local media report.
Saudi Arabia and Egypt have spoken about the possibility of sending ground troops.
Saudi Arabia has blockaded the Houthis, effectively cutting off their supply lines. By Thursday afternoon, the Saudis controlled Yemeni airspace, the adviser said, and the military threatened to destroy any naval ships trying to enter Yemeni ports.
Iran upset, Houthis defiant
Supreme leader Al Houthi spoke live Thursday night in Yemen on al-Masirah TV, saying, "If any army tries to invade our country, we will prove that Yemen will be a grave for those who invade us."
Iran denounced the military intervention. Marzieh Afkham, a spokeswoman for the country's Foreign Ministry, said the operation will throw an already complicated situation into further turmoil and disrupt chances at a peaceful resolution to Yemen's months-long internal strife. It also won't help a region already facing terrorist threats from groups like ISIS
and al Qaeda, she said.
"This is a dangerous action against international responsibilities to respect countries' national sovereignty," Afkham said, according to a report in Iran's state-run Islamic Republic News Agency.
At least one major player in Yemen besides the Houthis -- the General People's Congress, which is the party of longtime leader Ali Abdullah Saleh -- thinks the Saudis and their partners should stay out.
The GPC says the airstrikes have already led to civilian casualties. The best way to stop the bloodshed is to bring everyone to the negotiating table, the group said.