Leading a fleet of five helicopters surveying the damage from Hurricane Alicia, Texas Gov. Mark White cruised low over downtown Houston today, viewing the wreckage from walls of six glass towers that were shattered by the first hurricane of the season.

As seen from the air, the pace of life was picking up. But in the center of the nation's fifth largest city police were restricting pedestrians and traffic because of the danger that 400-pound panes of glass might fall from the affected buildings.

White expressed dismay at the sight of the shattered walls, saying damage would reach $100 million in downtown Houston alone.

Houston Mayor Kathy Whitmire, who toured the area with White, said it would be premature to question the modern design of the buildings. Because they are sheathed in glass they are especially vulnerable to hurricane-force winds.

Whitmire said, however, that city officials believe that the buildings may have been struck by flying chunks of stone, cement, roof tile and other debris. Only six buildings among more than two dozen glass towers in Houston suffered shattering damage, suggesting that winds alone probably were not responsible.

Flying south from the city across the flat bayou country of the Gulf of Mexico in his Huey helicopter, White saw the full effects of Alicia. Winds above 100 mph left hardly any community in the Houston-Galveston-Freeport triangle untouched.

President Reagan today declared Texas a major disaster area, clearing the way for additional federal assistance to hurricane victims. White said the president called him Thursday to express concern about the situation in Houston.

At an impromptu news conference after a touchdown at Galveston during the five-hour tour, White heard from the mayors of the small bedroom communities, historic fishing hamlets and booming petrochemical towns that line this part of Texas' gulf coast.

From the tiny rural hamlet of Pleak, pop. 250, in Fort Bend County to Texas City, a major petroleum refining center, the mayors, county judges and aldermen had little but praise for their citizens and requests for help as they attempt to rebuild their towns.

Communities like Jacinto City, La Porte, Columbus, Brenham, Kemah and Seabrook were scenes of lost roofs, stripped siding, overturned house trailers, sunken boats and even a light plane upside down at Galveston airport.

White refused to speculate whether the damage would reach a billion dollars, as some early estimates suggested, but his helicopter tour made clear that it will take many months, and in some cases years, before Alicia's effects are mended.

Many homes simply need new roof tiles or a rebuilt garage, but others are nothing more than piles of kindling. In Fort Bend County, Alicia laid waste valuable pecan groves that yield farmers millions of dollars a year. County Judge Jodie E. Stavinoha said it may be at least three years before the pecan trees can recover from having their branches torn off.

Expecting the worst, insurance companies today sent hundreds of claims adjusters to the area to set up emergency claims-handling systems. A spokesman for the Insurance Information Institute said that by midday about 300 adjusters had arrived to handle claims, and that many more are expected.

White said that almost every community he flew over "has significant damage. Some houses look like they were exploded from inside. We consider ourselves very blessed there was not a larger loss of life," he said, referring to the five deaths reported in Houston. No other deaths were reported along the gulf coast despite flooding and high winds and tides.

In recent years, said Col. Jim Adams, state director of public safety, the land south of Houston to the gulf coast has subsided closer to sea level because of petroleum extraction. Even though tides from Alicia did not reach record highs, he said, the fact that the land is lower now than during the last major hurricane here in 1979 made the danger potentially greater.

Adams said the state has pioneered in setting up a computerized system to predict the effects of tidal surges caused by hurricanes, however. The system, called the Sea Lake Overland Surges Caused by Huricanes (SLOSH), began issuing telex warnings to all Galveston-area police departments Tuesday afternoon.

Alicia sat in the gulf until late Wednesday, then crashed ashore, hitting hardest Galveston, Freeport and the hamlets in between, along with Houston.

Adams said there easily could have been much greater loss of life if the hurricane had been stronger.

"The strength of Alicia was at the lower level of hurricanes," he said. "But if those winds had reached 140 mph it is likely there would have been substantial loss of life from flooding in Galveston and elsewhere."

Today Galveston remained without power, and 75 National Guard members have joined the city's 440-member police force to protect against looting. Police reported that 22 persons have been apprehended in Galveston on suspicion of looting since Thursday night.

Houston police called in 100 off-duty detectives to increase patrols of businesses left accessible to thieves when winds shattered windows and doors and left burglar alarms inoperable. About 60 persons so far have been arrested on looting charges, police said.

In the nearby communities in Galveston County such as Jamaica Beach, La Marque, Santa Fe, Hitchcock and League City, the mayors said their major problems were with water shortages, lack of sanitary facilities, closed food stores and continued electrical failure.

Mayor Dorothy Childress of Hitchcock, a community of about 9,000, said she had used a state law to ban price gouging by the few merchants open for business. She said she acted after hearing of flashlight batteries being sold for $5 apiece. White seemed outraged by these reports and asked that state officials be made aware of any price gouging.

The governor led the helicopters across the agricultural flatlands of stricken Brazoria County, southwest of Galveston. Thousands of acres of soybeans, cotton and rice were knocked flat or almost submerged in flooded fields. Cattle grazed knee-deep in flooded pastures.

Brazoria County officials said that about half of their valuable crops of cotton, soybeans, rice and pecans had been lost.

After returning to Houston, the governor said his impression before the aerial tour had been that the damage from the hurricane was relatively light. But afterward he said, "It is worse than I had imagined. There is a tremendous debris problem, a problem with restoration of electricity throughout the area, and water pressure problems. Most of the city of Houston is shut down now and there's no estimate of how much money has been lost through lost man-hours of work."

Galveston was the hardest hit of all the communities he saw, he said, adding, "It will be very difficult for the people there."