Shares of major airlines and hotels fell while security-related companies jumped sharply Thursday in the wake of morning rush-hour blasts that rocked the London subway system, killing at least 33 and injuring more than 350.

Shares of AMR Corp. (AMR), the parent of American Airlines, slipped by 56 cents, or almost 5 percent, to $11.66 in morning trading on the New York Stock Exchange (search), where shares of Delta Air Lines Inc. dropped by 18 cents, or 5 percent, to $3.30.

Marriot Internationa Inc.'s stock fell 73 cents, or 1 percent, to $68.10 on the NYSE, while shares of Starwood Resorts and Hotels Worldwide Inc. declined by 87 cents, or 1 percent, to $60.43.

"Bookings today will obviously not be good, but I'm sure they'll pick up again," said airline analyst Jim Corridore at Standard & Poor's in New York.

But he said the reaction from investors was to be expected, given their nervousness about terrorism's potential chilling effect on tourism. Barring any follow-up attacks, Corridore said he anticipates shares of airlines, hotels and other tourism-related companies to recover over the next couple of weeks.

Tour operators said that based on recent experiences with terror attacks — most notably the deadly train bombings in Madrid in March 2004 — would-be travelers hold off on making any plans and that the popularity of trips to the affected region wanes somewhat.

Robin Tauck, the president of Tauck World Discovery, an upscale tour operator based in Westport, Conn., said that trips to Spain have experienced "a soft period of sales in 2004 and 2005."

Tauck, which has a group of tourists in London and has other trips planned for later this summer, said no guests have cancelled upcoming trips.

"People are watching the news and making their own decisions," Tauck said.

Meanwhile, companies that make surveillance and bomb detection equipment saw a huge boost. Internet video company IPIX Corp. (IPIX) jumped 66 cents, or 24 percent, to $3.40. IPIX recently won a Pentagon contract to research and build a camera to be used in aerial surveillance.

Isonics Corp. (ISON), a maker of silicon wafers and an explosives detector designer, jumped 35 cents, or 11.6 percent, to $3.38.

However, shares of larger old-line U.S. defense companies, such as General Dynamics (GD), Northrop Grumman (NOC), were mostly lower on expectations that the blasts could boost spending on more high-tech security.

"It is obvious that homeland defense stocks would, unfortunately, rally about any news and concerns over terrorism," Fulcrum Global Partners analyst John Balliotti said in an interview.

Frank Husic, managing partner of Husic Capital Management, said he expected defense to be one of two sectors that could outperform on Thursday.

"It might suggest more military action in the future, more spending on things of that ilk," he said, adding that energy stocks would also outperform.

The U.S. defense sector also includes companies such as Lockheed Martin (LMT) and Rockwell Collins (COL). Lockheed, Rockwell Collins, General Dynamics and Northrop shares were all lower on the New York Stock Exchange.

"This will give the (Bush) administration more time to push for big changes, changes in strategy itself. This is a reminder of the homeland security threat," said Chuck Gabriel, analyst at Prudential Securities. "It reinforces the (Donald) Rumsfeld view and gives him ammunition to spear defense planning toward investment in homeland security, versus the kinds of weapons systems to fight 2 major wars simultaneously."

Makers of identification technology, such as Viisage Technology Inc. (VISGE), Identix Inc. (IDNX) and Cogent Inc. (COGT) got a modest boost from the London attacks.

Cogent shares rose 3.9 percent to $29.50, Viisage and Identix shares rose 7 percent and 4 percent to $5.16 and $5.38 a share, respectively.

Shares in Mace Security International Inc. (MACE), which makes Mace pepper spray as well as electronics surveillance products, rose 26 cents, or 10.6 percent, to $2.72.

Digital Recorders Inc. (TBUS), which makes law enforcement and security communications systems, rose 47 cents, or 21.1 percent, to $2.70.

Reuters and the Associated Press contributed to this report.