MILWAUKEE (AP) -- The Milwaukee County bus system urged its drivers, security guards and passengers to be extra vigilant for any suspicious behavior and unattended packages Thursday after a series of deadly explosions on London's transit systems.
But until the Milwaukee County Transit System learns of a specific threat or gets more orders from the federal government, ''I don't know that we'd do anything more,'' spokesman Joe Caruso said.
The Bush administration raised the terror alert to code orange for the nation's mass transit systems after the deadly rush-hour bus and subway bombings in London. The heightened alert covered regional and inner-city passenger rail, subways and city bus systems.
Lori Getter, a spokeswoman for the Wisconsin Division of Emergency Management, said U.S. homeland security officials told state representatives they knew of no credible threat to the United States or to Wisconsin.
''Citizens are being urged to remain vigilant, and if they see anything unusual to report it to authorities,'' she said.
Getter said the federal government did not specify how to enhance security for mass transit systems other than to encourage those systems and local law enforcement agencies to work together.
Milwaukee police spokeswoman Anne E. Schwartz said the department's officers weren't ''doing anything any differently'' Thursday than they had since the Sept. 11, 2001, terrorist attacks.
The attacks in London, though, prompted Joan Smith, 68, of Milwaukee, to change her travel plans Thursday. She and her family planned to leave on the 8:11 a.m. Amtrak train to Chicago but pushed back their departure to around 11 a.m. because they feared traveling during the morning rush hour.
''It's unsettling, very unsettling,'' she said. ''We wanted to take a nice train ride and you wake up and see that on TV.''
The attacks prompted the University of Wisconsin-Madison to try to track down perhaps fewer than a dozen students who may have been in London, university spokesman John Lucas said. Three students working as interns at Parliament in London were reached Thursday and were fine, he said.
It's too early to say whether the university would change its fall program of studies in London because of the attacks, Lucas said.
When Mary Ann Wallenfang of Germantown awoke Thursday and heard the news about the attacks, she and her husband quickly tried to call their daughter, a graduate student at the University of Surrey.
Their daughter, 30-year-old Mary Ellen, had heard the initial reports of an electrical problem in the subway and got on a bus instead, Mary Ann Wallenfang said. She had gone just a short distance when a friend called and told her that buses also were targeted, so she quickly got off the bus, Wallenfang said.
At Milwaukee's Mitchell International Airport, Mark Foreman, 57, of Milwaukee, said he wasn't going to let the London attacks change his travel plans. He was watching TV coverage of the attacks while waiting for a flight to Washington, D.C.
''I'm not going to let the terrorists change the way I live,'' he said.
Associated Press writers Carrie Antlfinger in Milwaukee and Robert Imrie in Wausau contributed to this report.
