People are showing solidarity with London with a symbol in the style of the Tube logo

A graphic showing support with London is circulating social media Wednesday, in the wake of the apparent terror attack in the British capital that left at least five people dead and 40 more injured.

The icon, emblazoned with the slogan "We are not afraid," is modeled after the logo for the London Underground, which marks stops for the public transit system across the city. It has been gaining steam on Twitter, often accompanied by the hashtags #WeAreNotAfraid, #LondonAttacks, and #Westminster.

The attack occurred just past 2:30 p.m. local time, when a lone assailant drove a car into civilians on Westminster Bridge, crashed into Parliament gates, and left the vehicle to continue on foot. The attacker fatally stabbed a police officer guarding the carriage gates at Parliament's entrance, and was immediately shot dead by other police.

Central London was put on lockdown after the attack, and police confirmed extra police officers will be on duty throughout the city.

Here's a sample of the tweets: