The rockets were apparently launched from the vicinity of nearby Hama airport, which is under government control.
Meanwhile, security forces in the central Syrian town of Hama have closed public squares and set up checkpoints.
But Hama residents reacted quickly to protect the city from any broader assault.
Hama is now a place of extremes: joyous and sad, defiant but fearful.
Meanwhile, U.N. observers in Hama found the atmosphere tense, the United Nations said.
CNN: Syria says it will allow U.N. to deliver humanitarian aid
Some of the most brazen destruction has occurred at the Roman city of Apamea, about 40 miles northwest of Hama.
To date, only four of Syria's 14 governorates constitute the major hubs of the protest movement: Homs, Hama, Idlib and Daraa.
Hundreds of refugees from across Syria - from Daraa, Homs, Hama and other cities - are now in the relatively safety of Lebanon.
BBC: Syria refugees tell of civilian misery in besieged Homs
Assad Asheq Mustafa, a former Syrian agriculture minister and former governor of Syria's central Hama province, and Walid al-Zoabi, a real estate entrepreneur from Dubai.
The key to the project, Ms. Haws said, was an innovation by Israeli photographer Ardon Bar-Hama, who developed for the Philharmonic a quicker system of capturing archival images with digital cameras.
Robert Mood, head of the mission, said 50 observers were in the country, "deployed in the provinces of Damascus, Homs, Aleppo, Hama, Idleb and Daraa, " the state-run Syrian Arab News Agency said.
Joshua Landis, director of the Center for Middle East Studies and associate professor of Middle Eastern studies at the University of Oklahoma, said Alawites live "cheek by jowl" near Sunnis in Homs, Hama and Idlib province in the west.
Officials from the United Nations and the Organization of Islamic Cooperation plan to go on a mission led by the Syrian government to the provinces of Homs, Hama, Tartous, Latakia, Aleppo, Deir Ezzor, Rif Damashq and Daraa to assess humanitarian needs.
Analysts long have said that there could be a turning point in Syria if the unrest that has raged in major provincial cities such as Homs, Hama, Daraa, and Deir Ezzor were to spread to the larger cities of Damascus and Aleppo.
"This is a matter of utmost urgency for the United Nations and all efforts are in place to make sure that we get the people on the ground as quickly as possible ... apart from Damascus, we have permanently based observers in Homs, Hama, Daraa and Idlib, so this process will continue, " said Neeraj Singh, the observer team's spokesman, on Sunday.
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