Mortar rounds fired by Iran-backed rebels in Yemen hit the Saudi border town of Najran on Tuesday, prompting a Saudi-led military coalition to warn it would strike back.
Al-Ekhbariya state television showed footage of cars with windows blown out, chunks torn from pavements, a building peppered with shrapnel and one completely charred room with a hole in the ceiling.
The mortar attack was confirmed by the coalition that has waged a campaign of air strikes against the Huthi Shiite rebels and their allies in Yemen since March 26.
Coalition spokesman Brigadier General Ahmed Assiri told Al-Arabiya news channel the rebels had "randomly" shelled Najran using "mortar rounds" and "Katyusha rockets", causing injuries at a field hospital outside the city, without giving details.
"The source of fire had been specified and artillery, tanks, Apache (fighter helicopters), and coalition jets are dealing with the situation which will not go unpunished," Assiri told Al-Arabiya.
He told state television the rebel fire hit "hospitals, schools and civilian homes".
In a statement on Twitter, Saudi Arabian Airlines announced that "all our flights from and to Najran were suspended today until further notice".
Al-Ekhbariya reported that the city's schools had been closed.
Saudi Arabia has reinforced the frontier with artillery, tanks and hilltop lookout posts to block any Huthi incursion from their traditional highland stronghold just across the border.
Saudi ground forces have repeatedly clashed with the rebels near the border with Yemen and its helicopters have seen action there.
Saudi forces on Thursday killed dozens of rebels from Yemen who launched their first major attack on the kingdom since the air war began, the defence ministry said.
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Three Saudi soldiers also died in the battle after the rebels targeted border observation posts, also on the Najran border.
Tuesday's assault was the first by the Huthis on an inhabited Saudi town.
Assiri accused the rebels of trying to sabotage a tentative coalition initiative announced on Monday for a humanitarian pause in air strikes to allow deliveries of aid.
"After yesterday's announcement of the humanitarian initiative, they want to express their rejection of any peace initiative, so they targeted Najran," he said.
"The coalition leadership seeks to calm the situation to pave the way for political" talks and aid deliveries, Assiri said.
"Unfortunately, these (rebel) militiamen thought they could exploit the situation."
Saudi Foreign Minister Adel al-Jubeir warned the rebels on Monday against taking advantage of any pause in the bombing.
Assiri called Tuesday's attacks on Najran "suicidal", warning that "all those who approach the border will be killed".
The assault on Najran came as Saudi Arabia's King Salman warned at a summit in Riyadh of the threat from Iran to regional stability.
The Huthis are allied with army units loyal to Yemen's former president Ali Abdullah Saleh.
They are battling loyalists of President Abedrabbo Mansour Hadi, who fled the rebels' southern advance for Riyadh in March.