Bomb squad officials have been deployed at Wiper party leader's Karen home to investigate a device that was thrown into his compound.
Karen OCPD Cunningham Suiyanka said an object that looked like a grenade was hurled into Kalonzo Musyoka's home around 2am Wednesday.
No one was injured, officials said.
A security guard said unknown people in two vehicles drove by the home, opened fire and hurled a device into the compound.
On Tuesday, Mr Musyoka skipped the 'swearing-in' of Nasa's 2017 presidential candidate Raila Odinga to the disappointment of thousands of supporters.
When he appeared outside his Karen home Tuesday morning the Nasa co-principal was cagey with details about plans for the day's proceedings.
Mr Musyoka, who had recently stated that he would take the "oath" alongside Nasa leader Raila Odinga, was non-committal if the event would take place.
"I don't want to say about that right now. This tactical withdrawal by the police, we don't know. But our supporters must remain calm," he said in a brief interview with journalists who had camped outside his house.
He was accompanied by Kitui Senator Enoch Wambua and Makueni Governor Kivutha Kibwana, who did not address the press.
Mr Musyoka said he and the other Nasa leaders Moses Wetang'ula, Musalia Mudavadi and Mr Odinga would have a consultative meeting before heading to Uhuru Park.
"We are actually going into consultations. We have to look at the oath itself and release the details. We will let the country know the next move," he said. "This a very important struggle so we are still consulting. The media is under serious attack and we must tell our people what is happening," Mr Musyoka added.
He later held another briefing, where he accused the government of withdrawing Nasa leaders' security.
Read the original article on Nation.
Why Do This to Baba? Nasa Supporters Ask Kalonzo
Raila Odinga Takes 'Oath' as 'People's President'
AllAfrica publishes around 600 reports a day from more than 150 news organizations and over 500 other institutions and individuals, representing a diversity of positions on every topic. We publish news and views ranging from vigorous opponents of governments to government publications and spokespersons. Publishers named above each report are responsible for their own content, which AllAfrica does not have the legal right to edit or correct.
Articles and commentaries that identify allAfrica.com as the publisher are produced or commissioned by AllAfrica. To address comments or complaints, please Contact us.
AllAfrica is a voice of, by and about Africa - aggregating, producing and distributing 600 news and information items daily from over 150 African news organizations and our own reporters to an African and global public. We operate from Cape Town, Dakar, Abuja, Monrovia, Nairobi and Washington DC.