The number of Utahns called to active duty in support of Operation Desert Shield increased again during the past week with 12 firefighters from the Utah Air National Guard called up Tuesday and about 130 Marine Corps reservists activated Sunday.

Meanwhile, elements of another Air Guard unit were placed on alert Thursday for possible activation.One dozen members of the 151st Civil Engineering Squadron, based at the Salt Lake International Airport, have been assigned to Castle Air Force Base in California to replace active duty Air Force personnel that have been sent to the Persian Gulf. The firefighting squadron is expected to remain in California for the duration of their 180-day active duty tour.

About 130 Marine Reservists from the 4th Marine Division, 23rd Regiment, Second Battalion, Company F, were called to active duty Sunday and are expected to spend their active duty time in Okinawa.

Members of the Air Guard's 151st Air Refueling Group have been participating in Persian Gulf operations on a voluntary basis since Aug. 6, flying the group's aerial refueling tankers on missions that have lasted as long as one month. But Thursday the Guard announced elements of the Group, the 191st Air Refueling Squadron and the 151st Consolidated Aircraft Maintenance Squadron, have been placed on alert for a possible call-up. The alert affects fewer than 100 people, said Group Commander Col. Gordon Hill.