London ? This time, there was no carnage, no bombed-out trains or buses, no makeshift triage centers on the sidewalks. But for the legions of people who rely on London’s public transport system, the suffocating sense of fear Thursday afternoon was the same.

Although only a single person was reported injured by four small bombs that exploded during the lunch hour, the heart of the British capital was quickly seized by gridlock and uncertainty, noisy with the familiar sounds of wailing ambulances and hovering helicopters. The cellular networks quickly became overloaded again as people dialed nervously for answers.

Was there really a nail bomb on the Tube? Had another bus been blown to smithereens? Was it true that police had chased one of the bombers into a hospital, wires still sticking out of his shirt?

The hundreds of police officers who roped off the crime scenes weren’t talking, so the surplus of rumors and shortage of facts only fueled the collective anxiety.

For 10 solid minutes, Nicky Bhatt, 45, a resident from the suburb of Ealing, paced indecisively in front of the turnstiles at the Baker Street subway station after police said someone had tried to set off an “explosive device” at the Warren Street station several blocks away. “Do I go down there and chance the bombs and more chaos?” she asked. “Or do I try to take a taxi, even though that’s looking impossible right now?”

“You don’t want to give in to them. You don’t want them to win,” Bhatt said, trying to reassure herself. “But all the time, you hear more and more police cars out there, so you wonder if there are more bombs.” She put her subway ticket away and walked outside.

At the same subway stop, Fran Wittich-Broadley, a 27-year-old auditor lugging around a heavy black briefcase, made a different decision. She walked briskly down the stairs leading to the trains, but not without reservations. “It scares me,” she said, the worry evident in her eyes. “Actually, I’m petrified. But I need to go back to work. And I have no other chance of getting out of here. What can I do?”

If police were right in their preliminary statements that the goal was mass casualties, Thursday’s plot was an amateurish failure. There was no significant bloodshed. The incidents occurred at midday, when use of subway trains and buses is usually light. The sum total of the physical damage was less than a two-car accident.

But in terms of spreading fear and provoking chaos, the assaults had the desired effect. For the rest of the day, the sidewalks of London were clotted with commuters and tourists trying to figure out how to reach their destinations, blocked by a shifting array of subway shutdowns and police barricades across streets.

Along normally bustling Piccadilly Circus and Oxford Street, the evening rush hour brought more problems. Riders jockeyed to squeeze aboard packed buses, only to discover that congestion was so bad that the buses were moving just a few feet every 20 minutes or so.

Giving up and deciding to hoof it instead, people besieged police on street corners and at the cordoned-off areas for directions to points sometimes several miles away. Tourists with fold-out maps suddenly found themselves surrounded by anxious Londoners asking for a look.

Many pedestrians appeared more frustrated than fearful, as they walked for blocks only to encounter another police roadblock and orders to head in a different direction.

“You have to go all the way around,” a policeman told a weary woman trying to duck under the police tape stretched across a street.

“By foot?” she asked.

“Unless you can fly,” came the reply.

The scale and seriousness of the plot took a while to sink in. At the Warren Street station in central London, people evacuated the subway in an orderly manner. People aboveground saw no sign that anything was amiss until police officers arrived several minutes after 1 p.m. and started giving orders to leave the immediate vicinity.

At the nearby Prince of Wales Feathers pub, most of the 40 or so patrons who had gathered to watch a cricket match over lunch didn’t pay much mind at first to the burgeoning police presence. An officer told the drinkers to stay inside, without saying why, but returned 10 minutes later and instructed them to leave the area.

“It didn’t look like anything out of the ordinary,” said Liam Rodgers, a bartender at the pub. “Even now, it seems strange. You’d think it would be rush hour if they were going to do something like this again.”

A couple of blocks away, on Tottenham Court Road, stores emptied and doors were locked as police gradually ordered pedestrians to clear the blocks surrounding the nearby Warren Street station and hospital. Shop clerks peered anxiously from behind darkened cafe windows, while office workers gathered on a rooftop terrace to try to get a better look.

Stragglers in the street held up their mobile phones to snap and send photographs of the police helicopters whirring overhead, blithely ignoring police entreaties to “get back for your own safety.”

Ignoring a manager’s advice to stay inside, three young Australian laborers slipped out of the office building where they were moving furniture. “People are scared,” said Joel Greene, 24, of Melbourne. “Some of the girls up there are crying. Nobody knows what’s going on – we just heard sirens. The manager said it was a nail bomb.”

While signs of overt panic were few, it was apparent across London that an increased sense of vulnerability had sunk in.

On one double-decker bus route in south London, the driver was forced to stop suddenly when passengers reported an unattended gray duffel bag on the floor. When no one claimed the bag immediately, the bus emptied in a panic – until a middle-aged man stepped forward and sheepishly admitted that the bag was his.

As the riders filed slowly back onto the bus, one woman let loose with frustration. She walked up to the forgetful passenger and screamed obscenities in his face.

“You should be skinned alive!” she shouted. “How could you do that to people? You should be arrested!”

Nobody intervened.