The New York City Police Department is stepping up its presence at synagogues and in Jewish neighborhoods the wake of yesterday's deadly bus bombing in Bulgaria.

Police said as many as 100 critical response vehicles have been deployed.

They said they have not received any specific threats against the city.

Six people were killed and more than 30 were injured when a suicide bomber attacked a bus full of Israeli tourists in Sarafovo, Bulgaria.

Bulgaria's interior minister says the suspect appeared on security camera tape near the bus for almost an hour before the attack.

Israeli Prime Minister Benjamin Netanyahu blamed Iran and Hezbollah for the bombing but Iran's state TV called the claim ridiculous.

"It is a tragedy and I met with the Israeli ambassador this morning to get a briefing. The [police department] is all over it, both in Europe and in Israel and here, but you won't see anything different," Mayor Michael Bloomberg said.

Residents of the Upper East Side told NY1 this morning that increased police presence has become a routine sight.

"I think there's usually a very large police presence in this neighborhood anyway, so I didn't really notice that much of a difference. I mean, I do notice sometimes that they're more here than in others, there's more of a presence, but I think it's to be expected," said an Upper East Side local.

City police took similar precautions in March, after three children and a rabbi were gunned down in Toulouse, France.