Brussels residents turned to Twitter to offer people stranded in the Belgian capital rooms and transport after twin attacks on the airport and a rush-hour metro train killed at least 34 people on Tuesday.
A new Twitter account called "Brussels Lift" was created to offer practical help by connecting "people who need to travel with drivers who have empty seats".
People were using the hashtag #BrusselsLift to ask for rides and offer car spaces.
"I'm driving from Brussels to Meise (or anywhere else needed) later today, let me know if I can assist," Twitter user Virginia De Klippel said.
Other offers included #ikwillhelpen (I want to help) and tags such as #PorteOuverte and #OpenHouse, first used to show solidarity with Paris after November's attacks in which 130 died.
The Brussels blasts, close to European Union institutions, triggered security alerts across Europe and halted some cross-border transport.
Police cordoned off a wide area around the glass and steel EU buildings, putting soldiers on streets that lead down the main avenue through the area where the metro explosion took place and blocking access from Brussels' main park.
A road tunnel running through the area was also closed. No trams or buses were running and some people walked long distances across the city get home.
Flights in and out of Brussels were canceled and the city went into lockdown with the government urging people to stay put.
Facebook activated its "safety check" feature after the attacks, enabling users to reassure friends and relatives.
People used the hashtags #JeSuisBelge (I am Belgian) and #JeSuisBruxelles (I am Brussels) to express solidarity.
Plantu, the celebrated cartoonist for French newspaper Le Monde, drew a figure in the red, white and blue of the French flag hugging another in the red, gold and black tricolor of Belgium, both in tears.
(Editing by Ruth Pitchford)