Top US diplomat John Kerry has flown in to Riyadh for talks on a "humanitarian pause" in Yemen, where dozens of people were reported killed trying to flee worsening conditions after weeks of war.
On the Saudi side of the border there were more casualties as well, when shelling from Yemen killed five people, the civil defence agency said.
Riyadh has said it is considering temporary halts in air raids to allow aid deliveries into Yemen, where a Saudi-led coalition took action on March 26 in an effort to halt an advance by Iran-backed rebels.
Twenty-two humanitarian organisations warned their emergency aid operations in Yemen could cease because of fuel shortages. They urged an immediate opening of roads as well as an end to the coalition's air and sea blockades.
There has been growing concern for civilians in the war.
Yesterday, 32 people were reported to have died while trying to flee the southern city of Aden by sea.
Before he travelled to Saudi Arabia, Kerry told reporters in Djibouti he would raise the issue of a temporary halt to air strikes with officials in Riyadh.
"We will be discussing the nature of the pause and how it might be implemented," said Kerry, who held talks with Saudi Crown Prince Mohammed bin Nayef yesterday night and was to meet King Salman today.
"We are deeply concerned about the humanitarian situation that is unfolding in Yemen... For the time being the immediate crisis is the humanitarian one," Kerry said.
As well as international concern over the growing civilian death toll from the air campaign and fighting, deliveries of fuel, food and medicine have been severely crippled in the impoverished Arabian Peninsula nation.
Yemen's Foreign Minister Riyadh Yassin told reporters in the Saudi capital that he hoped today to also hold talks with Kerry, "especially about the humanitarian aid to Yemen. We hope tomorrow to discuss how we can go forward."
The United Nations says at least 1,200 people have been killed in Yemen since March 19, roughly half of them civilians.
The air strikes began as anti-government fighters approached Aden, forcing President Abedrabbo Mansour Hadi to flee to Riyadh.
The new UN envoy for Yemen, Ismail Ould Cheikh Ahmed, is to follow Kerry to Riyadh today in a bid to relaunch peace talks.
Thousands have fled Yemen, many to Djibouti in the Horn of Africa across the Bab al-Mandeb, a key shipping channel.
The war hit home in Saudi Arabia for a second day yesterday.
The civil defence department said four civilians and a prison security officer were killed by shells fired from Yemen at the border city of Najran.
The bombing came a day after the interior ministry said three people were killed in Najran in cross-border mortar and rocket attacks by the Huthis.
