Mother receives text from son in Lindt cafe under siege

A Sydney mother has told of the chilling text message she has received from her son - who is being held hostage inside the Lindt Chocolate Cafe.

'Mum I’m in the Lindt cafe in Sydney' read the text message, mother Mel told 2GB radio.

“My heart stopped, I sent back a text message: 'What is going on? Are you okay.'”

The last contact she had with her son was a reply text message, reading: “I’m okay mum, can’t talk”.

A Lindt employee says she saw a "look of terror" in the hostages pressed against glass after a Lindt cafe in Martin Place was taken over by an alleged gunman.

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Employee Elleanor Gillard told ABC she saw terrified faces of two hostages who were forced up against the glass.

"I'm just thinking about the guys in Lindt. The people we see everyday, go in and buy our coffee from them, and I'm sure they're terrified," she said.

"It must be horrible for them. We're safe. There is nobody pointing a gun at us."

Ms Gillard said police told them not to leave and "just to stay away from the doors, stay inside".

"We've just been notifying everyone on the floors above, where I am I'm on the ground, not to come down in the lift because the lifts open up right in the foyer between us and Lindt," she said.

VIDEO: Hostages escape Martin Place Lindt siege

Patrick Burns from Channel 7 said: "We all raced to the window and there we saw the shocking and chilling sight of people putting their hands up against the panes of glass at the cafe."

It's believed at least 13 hostages are being held in the cafe, where a black flag with white Arabic writing was reportedly brandished across the window.

Witness Bruno said he works at the Lindt cafe and that the doors were locked when he arrived, ABC reported.

"I walked up to the door and it was locked ... I've called people and they haven't answered phone ... it's pretty bad," he said.

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A woman who often goes inside the Lindt cafe for coffee decided today to get her coffee somewhere else.

"I just walked up from Martin Place station, up the stairs to get my coffee at the Lindt cafe, and for some reason this morning I decided to get it at the station underneath," she said.

"It's very worrying. You just don't think these sorts of things are going to happen in your own backyard. It's literally frightening."

A nearby legal firm has been evacuated and the NSW Department of Justice has cancelled all court today.

Channel Seven News producer Christy Johns said she "looked out the window and all the workers had their hands pinned up against the glass."

"There were cops surrounding the building, people running out of the building.

"When the flag went up, our hearts just sank.

"The cops stormed into the building and forced us into the back of the room," she said.

Martin Place was initially named as a potential target during terror raids earlier this year.

Hotline information:

For general information about the siege at Martin place – call the Public Information and Inquiry Centre: 1800 227 228

To report any suspicious activities – call the National Security Hotline: 1800 1234 00

For transport updates – call: 131 500

For emergencies – call: 000

Morning news break – December 15