Al Jazeera, reporting from Riyadh, said Saudi Arabia's defense ministry announced on Monday that a "massive" force had reached Najran on its way to taking its position on the frontlines adjacent to Yemeni territory, following Monday's exchange of fire.
The ministry did not specify the size of the force assembled but stated that it included advanced armaments capable of fighting in rugged mountainous areas, the report added.
Footage showing rows of tanks and armoured personnel carriers loaded on military vehicles headed towards Yemen were aired on a Saudi-owned television channel.
The Houthis said they fired Katyusha rockets and mortars on the Saudi cities of Jizan and Najran earlier on Monday, after Saudi forces hit Sa'dah and Hajjah provinces with more than 150 rockets.
Saudi Arabia's civil defence department said one Saudi national was killed in the shelling in Najran.
Another Saudi citizen and three expatriates were also injured in the fire, the department said.
Also, fighter jets from the Arab coalition struck positions of the Houthis in the central city of Taiz and in the oil-producing Marib province east of the capital, Sana'a.
There were no immediate details on any casualties.