A man who was seriously wounded Monday night by a Montgomery County police officer has had mental problems and acted strangely at two fast food restaurants earlier in the day, police said yesterday.

Michael Lorenz, 38, of Philadelphia, who was shot in the chest and grazed in the arm, was in serious but stable condition yesterday at Suburban Hospital in Bethesda, a hospital spokeswoman said.

Police obtained warrants for Lorenz yesterday, charging him with assault with intent to murder and destruction of property. Lorenz, who is under police guard, will be arrested upon his release from the hospital.

Lorenz was shot twice shortly after 8:45 p.m. Monday by Officer Robert Hellmuth after a report of a disorderly man at a Long & Foster realty office in the 11600 block of Rockville Pike.

Five people ran from the office when Lorenz walked in and began throwing furniture, police said. Although initially calm when approached by Hellmuth, Lorenz did a "complete turnaround" and tossed a telephone and wooden, swivel chair at the officer, police spokeswoman Ann Evans said.

Hellmuth, an 18-year veteran, fired four shots when the suspect charged at him, Evans said. The officer was not injured. Lorenz, who had rocks in his pockets, did not have a weapon, police said.

Evans said Lorenz's father told police yesterday he last saw his son Sunday in Philadelphia. According to Evans, the father said Lorenz was "acting strangely" and has been taking medication for a chemical imbalance.

Yesterday, workers at two fast food restaurants said a man fitting Lorenz's description had been in and out of their eateries throughout the day on Monday. A detective said police think that Lorenz "had been hanging out" at the restaurants before the shooting.

Victor Diggs, a manager at Popeye's, said he called police about 1:30 p.m. Monday for a man resembling Lorenz "who was taking a bath in the bathroom. The water was running out into the dining area." Diggs said the man "mumbled a lot" and refused to leave until police arrived.

Workers at Arby's restaurant, between Popeye's and Long & Foster, said a barefoot man resembling Lorenz was standing outside the door when the restaurant opened about 10:30 a.m. Workers said the unkempt man sat in a corner booth "talking to himself but not bothering customers. He walked inside and outside a couple of times and ordered some coffee."

Dorothy Kalbfus, manager at Long & Foster, said the three real estate agents and two customers who had been in the office when Lorenz arrived did not know him. Police said Lorenz, muttering incoherently, knocked over furniture while walking to the rear of the office.

Hellmuth has been placed on routine administrative leave pending an investigation, Evans said.